voku\db\DB

Complexity

Total Complexity

361

Size/Duplication

Total Lines	2678
Duplicated Lines	8.4 %

Coupling/Cohesion

Components	2
Dependencies	14

Test Coverage

Coverage

75.64%

Importance

Changes

0

61 Methods

Rating	Name	Duplication	Size	Complexity
B	__construct()	0	60	1
A	__clone()	0	3	1
A	__destruct()	0	7	2
A	__invoke()	0	4	2
A	__wakeup()	0	4	1
B	_loadConfig()	0	55	7
F	_parseArrayPair()	14	163	44
B	_parseQueryParams()	0	34	6
B	_parseQueryParamsByName()	0	46	8
A	affected_rows()	0	12	3
B	beginTransaction()	32	32	7
A	clearErrors()	0	4	1
B	close()	0	37	6
B	commit()	28	28	6
C	connect()	0	95	13
A	connect_helper()	0	19	4
B	delete()	31	31	6
B	endTransaction()	0	31	7
A	errors()	0	6	2
F	escape()	7	107	24
B	execSQL()	25	46	10
A	getAllTables()	0	9	1
A	getConfig()	0	21	2
A	getDebugger()	0	4	1
A	getDoctrineConnection()	0	4	1
A	getDoctrinePDOConnection()	11	11	3
A	getErrors()	0	4	1
C	getInstance()	0	80	12
A	getInstanceDoctrineHelper()	0	25	1
A	getLink()	0	4	1
A	get_charset()	0	4	1
A	inTransaction()	0	4	1
B	insert()	0	34	6
A	insert_id()	0	13	3
A	isDoctrineMySQLiConnection()	0	11	3
A	isDoctrinePDOConnection()	11	11	3
A	isReady()	0	4	2
A	lastError()	0	6	2
F	multi_query()	0	126	24
A	num_rows()	0	14	3
B	ping()	0	20	6
A	prepare()	0	4	1
A	qry()	0	25	2
F	query()	0	141	24
B	queryErrorHandling()	0	44	7
A	quote_string()	0	13	1
A	reconnect()	0	14	3
B	replace()	0	42	7
B	rollback()	29	29	6
C	secure()	7	63	13
B	select()	30	30	6
A	select_db()	0	19	5
C	setConfigExtra()	0	38	10
B	set_charset()	0	41	10
A	set_convert_null_to_empty_string()	0	6	1
A	set_mysqli_report()	0	12	3
B	showConfigError()	0	35	9
A	startTransaction()	0	4	1
A	table_exists()	0	10	3
A	transact()	0	23	4
B	update()	0	44	7

<?php

declare(strict_types=1);

namespace voku\db;

use Doctrine\DBAL\Connection;
use voku\cache\Cache;
use voku\db\exceptions\DBConnectException;
use voku\db\exceptions\DBGoneAwayException;
use voku\db\exceptions\QueryException;
use voku\helper\UTF8;

/**
 * DB: This class can handle DB queries via MySQLi.
 */
final class DB
{
    /**
     * @var int
     */
    public $query_count = 0;

    /**
     * @var \mysqli|null
     */
    private $mysqli_link;

    /**
     * @var bool
     */
    private $connected = false;

    /**
     * @var array
     */
    private $mysqlDefaultTimeFunctions;

    /**
     * @var string
     */
    private $hostname = '';

    /**
     * @var string
     */
    private $username = '';

    /**
     * @var string
     */
    private $password = '';

    /**
     * @var string
     */
    private $database = '';

    /**
     * @var int
     */
    private $port = 3306;

    /**
     * @var string
     */
    private $charset = 'utf8';

    /**
     * @var string
     */
    private $socket = '';

    /**
     * @var int|null
     */
    private $flags;

    /**
     * @var bool
     */
    private $session_to_db = false;

    /**
     * @var bool
     */
    private $in_transaction = false;

    /**
     * @var bool
     */
    private $convert_null_to_empty_string = false;

    /**
     * @var bool
     */
    private $ssl = false;

    /**
     * The path name to the key file
     *
     * @var string
     */
    private $clientkey;

    /**
     * The path name to the certificate file
     *
     * @var string
     */
    private $clientcert;

    /**
     * The path name to the certificate authority file
     *
     * @var string
     */
    private $cacert;

    /**
     * @var Debug
     */
    private $debug;

    /**
     * @var \Doctrine\DBAL\Connection|null
     */
    private $doctrine_connection;

    /**
     * @var int
     */
    private $affected_rows = 0;

    /**
     * __construct()
     *
     * @param string $hostname
     * @param string $username
     * @param string $password
     * @param string $database
     * @param int    $port
     * @param string $charset
     * @param bool   $exit_on_error         <p>Throw a 'Exception' when a query failed, otherwise it will return
     *                                      'false'. Use false to disable it.</p>
     * @param bool   $echo_on_error         <p>Echo the error if "checkForDev()" returns true.
     *                                      Use false to disable it.</p>
     * @param string $logger_class_name
     * @param string $logger_level          <p>'TRACE', 'DEBUG', 'INFO', 'WARN', 'ERROR', 'FATAL'</p>
     * @param array  $extra_config          <p>
     *                                      'session_to_db' => bool<br>
     *                                      'doctrine'      => \Doctrine\DBAL\Connection<br>
     *                                      'socket'        => string (path)<br>
     *                                      'flags'         => null|int<br>
     *                                      'ssl'           => bool<br>
     *                                      'clientkey'     => string (path)<br>
     *                                      'clientcert'    => string (path)<br>
     *                                      'cacert'        => string (path)<br>
     *                                      </p>
     */
    private function __construct(
        string $hostname,
        string $username,
        string $password,
        string $database,
        $port,
        string $charset,
        bool $exit_on_error,
        bool $echo_on_error,
        string $logger_class_name,
        string $logger_level,
        array $extra_config = []
    ) {
        $this->debug = new Debug($this);

        $this->_loadConfig(
            $hostname,
            $username,
            $password,
            $database,
            $port,
            $charset,
            $exit_on_error,
            $echo_on_error,
            $logger_class_name,
            $logger_level,
            $extra_config
        );

        $this->connect();

        $this->mysqlDefaultTimeFunctions = [
            // Returns the current date.
            'CURDATE()',
            // CURRENT_DATE	| Synonyms for CURDATE()
            'CURRENT_DATE()',
            // CURRENT_TIME	| Synonyms for CURTIME()
            'CURRENT_TIME()',
            // CURRENT_TIMESTAMP | Synonyms for NOW()
            'CURRENT_TIMESTAMP()',
            // Returns the current time.
            'CURTIME()',
            // Synonym for NOW()
            'LOCALTIME()',
            // Synonym for NOW()
            'LOCALTIMESTAMP()',
            // Returns the current date and time.
            'NOW()',
            // Returns the time at which the function executes.
            'SYSDATE()',
            // Returns a UNIX timestamp.
            'UNIX_TIMESTAMP()',
            // Returns the current UTC date.
            'UTC_DATE()',
            // Returns the current UTC time.
            'UTC_TIME()',
            // Returns the current UTC date and time.
            'UTC_TIMESTAMP()',
        ];
    }

    /**
     * Prevent the instance from being cloned.
     *
     * @return void
     */
    private function __clone()
    {
    }

    /**
     * __destruct
     */
    public function __destruct()
    {
        // close the connection only if we don't save PHP-SESSION's in DB
        if (!$this->session_to_db) {
            $this->close();
        }
    }

    /**
     * @param string|null $sql
     * @param array       $bindings
     *
     * @return bool|DB|int|Result|string
     *                                      <p>
     *                                      "DB" by "$sql" === null<br />
     *                                      "Result" by "<b>SELECT</b>"-queries<br />
     *                                      "int|string" (insert_id) by "<b>INSERT / REPLACE</b>"-queries<br />
     *                                      "int" (affected_rows) by "<b>UPDATE / DELETE</b>"-queries<br />
     *                                      "true" by e.g. "DROP"-queries<br />
     *                                      "false" on error
     *                                      </p>
     */
    public function __invoke(string $sql = null, array $bindings = [])
    {
        return $sql !== null ? $this->query($sql, $bindings) : $this;
    }

    /**
     * __wakeup
     *
     * @return void
     */
    public function __wakeup()
    {
        $this->reconnect();
    }

    /**
     * Load the config from the constructor.
     *
     * @param string $hostname
     * @param string $username
     * @param string $password
     * @param string $database
     * @param int    $port                  <p>default is (int)3306</p>
     * @param string $charset               <p>default is 'utf8' or 'utf8mb4' (if supported)</p>
     * @param bool   $exit_on_error         <p>Throw a 'Exception' when a query failed, otherwise it will return
     *                                      'false'. Use false to disable it.</p>
     * @param bool   $echo_on_error         <p>Echo the error if "checkForDev()" returns true.
     *                                      Use false to disable it.</p>
     * @param string $logger_class_name
     * @param string $logger_level
     * @param array  $extra_config          <p>
     *                                      'session_to_db' => bool<br>
     *                                      'doctrine'      => \Doctrine\DBAL\Connection<br>
     *                                      'socket'        => string (path)<br>
     *                                      'flags'         => null|int<br>
     *                                      'ssl'           => bool<br>
     *                                      'clientkey'     => string (path)<br>
     *                                      'clientcert'    => string (path)<br>
     *                                      'cacert'        => string (path)<br>
     *                                      </p>
     *
     * @return bool
     */
    private function _loadConfig(
        string $hostname,
        string $username,
        string $password,
        string $database,
        $port,
        string $charset,
        bool $exit_on_error,
        bool $echo_on_error,
        string $logger_class_name,
        string $logger_level,
        array $extra_config = []
    ): bool {
        $this->hostname = $hostname;
        $this->username = $username;
        $this->password = $password;
        $this->database = $database;

        if ($charset) {
            $this->charset = $charset;
        }

        if ($port) {
            $this->port = (int) $port;
        } else {
            /** @noinspection PhpUsageOfSilenceOperatorInspection */
            $this->port = (int) @\ini_get('mysqli.default_port');
        }

        // fallback
        if (!$this->port) {
            $this->port = 3306;
        }

        /** @noinspection PhpUsageOfSilenceOperatorInspection */
        if (
            !$this->socket
            &&
            ($defaultSocket = @\ini_get('mysqli.default_socket'))
            &&
            \is_readable($defaultSocket)
        ) {
            $this->socket = $defaultSocket;
        }

        $this->debug->setExitOnError($exit_on_error);
        $this->debug->setEchoOnError($echo_on_error);

        $this->debug->setLoggerClassName($logger_class_name);
        $this->debug->setLoggerLevel($logger_level);

        $this->setConfigExtra($extra_config);

        return $this->showConfigError();
    }

    /**
     * Parses arrays with value pairs and generates SQL to use in queries.
     *
     * @param array  $arrayPair
     * @param string $glue <p>This is the separator.</p>
     *
     * @return string
     *
     * @internal
     */
    public function _parseArrayPair(array $arrayPair, string $glue = ','): string
    {
        // init
        $sql = '';

        if (\count($arrayPair) === 0) {
            return '';
        }

        $arrayPairCounter = 0;
        foreach ($arrayPair as $_key => $_value) {
            $_connector = '=';
            $_glueHelper = '';
            $_key_upper = \strtoupper((string) $_key);

            if (\strpos($_key_upper, ' NOT') !== false) {
                $_connector = 'NOT';
            }

            if (\strpos($_key_upper, ' IS') !== false) {
                $_connector = 'IS';
            }

            if (\strpos($_key_upper, ' IS NOT') !== false) {
                $_connector = 'IS NOT';
            }

            if (\strpos($_key_upper, ' IN') !== false) {
                $_connector = 'IN';
            }

            if (\strpos($_key_upper, ' NOT IN') !== false) {
                $_connector = 'NOT IN';
            }

            if (\strpos($_key_upper, ' BETWEEN') !== false) {
                $_connector = 'BETWEEN';
            }

            if (\strpos($_key_upper, ' NOT BETWEEN') !== false) {
                $_connector = 'NOT BETWEEN';
            }

            if (\strpos($_key_upper, ' LIKE') !== false) {
                $_connector = 'LIKE';
            }

            if (\strpos($_key_upper, ' NOT LIKE') !== false) {
                $_connector = 'NOT LIKE';
            }

            if (\strpos($_key_upper, ' >') !== false && \strpos($_key_upper, ' =') === false) {
                $_connector = '>';
            }

            if (\strpos($_key_upper, ' <') !== false && \strpos($_key_upper, ' =') === false) {
                $_connector = '<';
            }

            if (\strpos($_key_upper, ' >=') !== false) {
                $_connector = '>=';
            }

            if (\strpos($_key_upper, ' <=') !== false) {
                $_connector = '<=';
            }

            if (\strpos($_key_upper, ' <>') !== false) {
                $_connector = '<>';
            }

            if (\strpos($_key_upper, ' OR') !== false) {
                $_glueHelper = 'OR';
            }

            if (\strpos($_key_upper, ' AND') !== false) {
                $_glueHelper = 'AND';
            }

            if (\is_array($_value)) {
                $firstKey = null;
                $firstValue = null;
                foreach ($_value as $oldKey => $oldValue) {
                    $_value[$oldKey] = $this->secure($oldValue);

                    if ($firstKey === null) {
                        $firstKey = $oldKey;
                    }

                    if ($firstValue === null) {
                        $firstValue = $_value[$oldKey];
                    }
                }

                if ($_connector === 'NOT IN' || $_connector === 'IN') {
                    $_value = '(' . \implode(',', $_value) . ')';
                } elseif ($_connector === 'NOT BETWEEN' || $_connector === 'BETWEEN') {
                    $_value = '(' . \implode(' AND ', $_value) . ')';
                } elseif ($firstKey && $firstValue) {
                    if (\strpos((string) $firstKey, ' +') !== false) {
                        $firstKey = \str_replace(' +', '', (string) $firstKey);
                        $_value = $firstKey . ' + ' . $firstValue;
                    }

                    if (\strpos((string) $firstKey, ' -') !== false) {
                        $firstKey = \str_replace(' -', '', (string) $firstKey);
                        $_value = $firstKey . ' - ' . $firstValue;
                    }
                }
            } else {
                $_value = $this->secure($_value);
            }

            $quoteString = $this->quote_string(
                \trim(
                    (string) \str_ireplace(
                        [
                            $_connector,
                            $_glueHelper,
                        ],
                        '',
                        (string) $_key
                    )
                )
            );

            $_value = (array) $_value;

            if (!$_glueHelper) {
                $_glueHelper = $glue;
            }

            $tmpCounter = 0;
            foreach ($_value as $valueInner) {
                $_glueHelperInner = $_glueHelper;

                if ($arrayPairCounter === 0) {
                    if ($tmpCounter === 0 && $_glueHelper === 'OR') {
                        $_glueHelperInner = '1 = 1 AND ('; // first "OR"-query glue
                    } elseif ($tmpCounter === 0) {
                        $_glueHelperInner = ''; // first query glue e.g. for "INSERT"-query -> skip the first ","
                    }
                } elseif ($tmpCounter === 0 && $_glueHelper === 'OR') {
                    $_glueHelperInner = 'AND ('; // inner-loop "OR"-query glue
                }

                if (\is_string($valueInner) && $valueInner === '') {
                    $valueInner = "''";
                }

                $sql .= ' ' . $_glueHelperInner . ' ' . $quoteString . ' ' . $_connector . ' ' . $valueInner . " \n";
                $tmpCounter++;
            }

            if ($_glueHelper === 'OR') {
                $sql .= ' ) ';
            }

            $arrayPairCounter++;
        }

        return $sql;
    }

    /**
     * _parseQueryParams
     *
     * @param string $sql
     * @param array  $params
     *
     * @return array
     *               <p>with the keys -> 'sql', 'params'</p>
     */
    private function _parseQueryParams(string $sql, array $params = []): array
    {
        $offset = \strpos($sql, '?');

        // is there anything to parse?
        if (
            $offset === false
            ||
            \count($params) === 0
        ) {
            return ['sql' => $sql, 'params' => $params];
        }

        foreach ($params as $key => $param) {

            // use this only for not named parameters
            if (!\is_int($key)) {
                continue;
            }

            if ($offset === false) {
                continue;
            }

            $replacement = $this->secure($param);

            unset($params[$key]);

            $sql = \substr_replace($sql, $replacement, $offset, 1);
            $offset = \strpos($sql, '?', $offset + \strlen((string) $replacement));
        }

        return ['sql' => $sql, 'params' => $params];
    }

    /**
     * Returns the SQL by replacing :placeholders with SQL-escaped values.
     *
     * @param string $sql    <p>The SQL string.</p>
     * @param array  $params <p>An array of key-value bindings.</p>
     *
     * @return array
     *               <p>with the keys -> 'sql', 'params'</p>
     */
    private function _parseQueryParamsByName(string $sql, array $params = []): array
    {
        // is there anything to parse?
        if (
            \strpos($sql, ':') === false
            ||
            \count($params) === 0
        ) {
            return ['sql' => $sql, 'params' => $params];
        }

        $offset = null;
        $replacement = null;
        foreach ($params as $name => $param) {

            // use this only for named parameters
            if (\is_int($name)) {
                continue;
            }

            // add ":" if needed
            if (\strpos($name, ':') !== 0) {
                $nameTmp = ':' . $name;
            } else {
                $nameTmp = $name;
            }

            if ($offset === null) {
                $offset = \strpos($sql, $nameTmp);
            } else {
                $offset = \strpos($sql, $nameTmp, $offset + \strlen((string) $replacement));
            }

            if ($offset === false) {
                continue;
            }

            $replacement = $this->secure($param);

            unset($params[$name]);

            $sql = \substr_replace($sql, $replacement, $offset, \strlen($nameTmp));
        }

        return ['sql' => $sql, 'params' => $params];
    }

    /**
     * Gets the number of affected rows in a previous MySQL operation.
     *
     * @return int
     */
    public function affected_rows(): int
    {
        if (
            $this->mysqli_link
            &&
            $this->mysqli_link instanceof \mysqli
        ) {
            return \mysqli_affected_rows($this->mysqli_link);
        }

        return (int) $this->affected_rows;
    }

    /**
     * Begins a transaction, by turning off auto commit.
     *
     * @return bool
     *              <p>This will return true or false indicating success of transaction</p>
     */
    public function beginTransaction(): bool

This method seems to be duplicated in your project.

    {
        if ($this->in_transaction) {
            $this->debug->displayError('Error: mysql server already in transaction!', false);

            return false;
        }

        $this->clearErrors(); // needed for "$this->endTransaction()"
        $this->in_transaction = true;

        if ($this->mysqli_link) {
            $return = \mysqli_autocommit($this->mysqli_link, false);
        } elseif ($this->doctrine_connection && $this->isDoctrinePDOConnection()) {
            $this->doctrine_connection->setAutoCommit(false);
            $this->doctrine_connection->beginTransaction();

            if ($this->doctrine_connection->isTransactionActive()) {
                $return = true;
            } else {
                $return = false;
            }
        } else {
            $return = false;
        }

        if (!$return) {
            $this->in_transaction = false;
        }

        return $return;
    }

    /**
     * Clear the errors in "_debug->_errors".
     *
     * @return bool
     */
    public function clearErrors(): bool
    {
        return $this->debug->clearErrors();
    }

    /**
     * Closes a previously opened database connection.
     *
     * @return bool
     *              Will return "true", if the connection was closed,
     *              otherwise (e.g. if the connection was already closed) "false".
     */
    public function close(): bool
    {
        $this->connected = false;

        if (
            $this->doctrine_connection
            &&
            $this->doctrine_connection instanceof \Doctrine\DBAL\Connection
        ) {
            $connectedBefore = $this->doctrine_connection->isConnected();

            $this->doctrine_connection->close();

            $this->mysqli_link = null;

            if ($connectedBefore) {
                return !$this->doctrine_connection->isConnected();
            }

            return false;
        }

        if (
            $this->mysqli_link
            &&
            $this->mysqli_link instanceof \mysqli
        ) {
            $result = \mysqli_close($this->mysqli_link);
            $this->mysqli_link = null;

            return $result;
        }

        $this->mysqli_link = null;

        return false;
    }

    /**
     * Commits the current transaction and end the transaction.
     *
     * @return bool
     *              <p>bool true on success, false otherwise.</p>
     */
    public function commit(): bool

This method seems to be duplicated in your project.

    {
        if (!$this->in_transaction) {
            $this->debug->displayError('Error: mysql server is not in transaction!', false);

            return false;
        }

        if ($this->mysqli_link) {
            $return = \mysqli_commit($this->mysqli_link);
            \mysqli_autocommit($this->mysqli_link, true);
        } elseif ($this->doctrine_connection && $this->isDoctrinePDOConnection()) {
            $this->doctrine_connection->commit();
            $this->doctrine_connection->setAutoCommit(true);

            if ($this->doctrine_connection->isAutoCommit()) {
                $return = true;
            } else {
                $return = false;
            }
        } else {
            $return = false;
        }

        $this->in_transaction = false;

        return $return;
    }

    /**
     * Open a new connection to the MySQL server.
     *
     * @throws DBConnectException
     *
     * @return bool
     */
    public function connect(): bool
    {
        if ($this->isReady()) {
            return true;
        }

        if ($this->doctrine_connection) {
            $this->doctrine_connection->connect();

            $doctrineWrappedConnection = $this->doctrine_connection->getWrappedConnection();

            if ($this->isDoctrineMySQLiConnection()) {
                \assert($doctrineWrappedConnection instanceof \Doctrine\DBAL\Driver\Mysqli\MysqliConnection);

                $this->mysqli_link = $doctrineWrappedConnection->getWrappedResourceHandle();

                return $this->connect_helper();
            }

            if ($this->isDoctrinePDOConnection()) {
                $this->mysqli_link = null;

                return $this->connect_helper();
            }
        }

        $flags = $this->flags;

        \mysqli_report(\MYSQLI_REPORT_STRICT);

        try {
            $this->mysqli_link = \mysqli_init();

It seems like \mysqli_init() of type object<mysql> is incompatible with the declared type object<mysqli>|null of property $mysqli_link.

            if (Helper::isMysqlndIsUsed()) {
                \mysqli_options($this->mysqli_link, \MYSQLI_OPT_INT_AND_FLOAT_NATIVE, true);
            }

            if ($this->ssl) {
                if (empty($this->clientcert)) {
                    throw new DBConnectException('Error connecting to mysql server: clientcert not defined');
                }

                if (empty($this->clientkey)) {
                    throw new DBConnectException('Error connecting to mysql server: clientkey not defined');
                }

                if (empty($this->cacert)) {
                    throw new DBConnectException('Error connecting to mysql server: cacert not defined');
                }

                \mysqli_options($this->mysqli_link, \MYSQLI_OPT_SSL_VERIFY_SERVER_CERT, true);

                \mysqli_ssl_set(
                    $this->mysqli_link,
                    $this->clientkey,
                    $this->clientcert,
                    $this->cacert,
                    '',
                    ''
                );

                $flags |= \MYSQLI_CLIENT_SSL;
            }

            /** @noinspection PhpUsageOfSilenceOperatorInspection */
            $this->connected = @\mysqli_real_connect(
                $this->mysqli_link,
                $this->hostname,
                $this->username,
                $this->password,
                $this->database,
                $this->port,
                $this->socket,
                (int) $flags
            );
        } catch (\Exception $e) {
            $error = 'Error connecting to mysql server: ' . $e->getMessage();
            $this->debug->displayError($error, false);

            throw new DBConnectException($error, 100, $e);
        }
        \mysqli_report(\MYSQLI_REPORT_OFF);

        $errno = \mysqli_connect_errno();
        if (!$this->connected || $errno) {
            $error = 'Error connecting to mysql server: ' . \mysqli_connect_error() . ' (' . $errno . ')';
            $this->debug->displayError($error, false);

            throw new DBConnectException($error, 101);
        }

        $this->set_charset($this->charset);

        return $this->isReady();
    }

    /**
     * @return bool
     */
    private function connect_helper(): bool
    {
        if (!$this->doctrine_connection) {
            $this->connected = false;
        } else {
            $this->connected = $this->doctrine_connection->isConnected();
        }

        if (!$this->connected) {
            $error = 'Error connecting to mysql server: ' . \print_r($this->doctrine_connection ? $this->doctrine_connection->errorInfo() : [], false);
            $this->debug->displayError($error, false);

            throw new DBConnectException($error, 101);
        }

        $this->set_charset($this->charset);

        return $this->isReady();
    }

    /**
     * Execute a "delete"-query.
     *
     * @param string       $table
     * @param array|string $where
     * @param string|null  $databaseName <p>Use <strong>null</strong> if you will use the current database.</p>
     *
     * @throws QueryException
     *
     * @return false|int
     *                   <p>false on error</p>
     */
    public function delete(string $table, $where, string $databaseName = null)

This method seems to be duplicated in your project.

    {
        // init
        $table = \trim($table);

        if ($table === '') {
            $this->debug->displayError('Invalid table name, table name in empty.', false);

            return false;
        }

        if (\is_string($where)) {
            $WHERE = $this->escape($where, false);
        } elseif (\is_array($where)) {
            $WHERE = $this->_parseArrayPair($where, 'AND');
        } else {
            $WHERE = '';
        }

        if ($databaseName) {

The expression $databaseName of type null|string is loosely compared to true; this is ambiguous if the string can be empty. You might want to explicitly use !== null instead.

            $databaseName = $this->quote_string(\trim($databaseName)) . '.';
        }

        $sql = 'DELETE FROM ' . $databaseName . $this->quote_string($table) . " WHERE (${WHERE})";

        $return = $this->query($sql);

        \assert(\is_int($return) || $return === false);

        return $return;
    }

    /**
     * Ends a transaction and commits if no errors, then ends autocommit.
     *
     * @return bool
     *              <p>This will return true or false indicating success of transactions.</p>
     */
    public function endTransaction(): bool
    {
        if (!$this->in_transaction) {
            $this->debug->displayError('Error: mysql server is not in transaction!', false);

            return false;
        }

        if (!$this->errors()) {
            $return = $this->commit();
        } else {
            $this->rollback();
            $return = false;
        }

        if ($this->mysqli_link) {
            \mysqli_autocommit($this->mysqli_link, true);
        } elseif ($this->doctrine_connection && $this->isDoctrinePDOConnection()) {
            $this->doctrine_connection->setAutoCommit(true);

            if ($this->doctrine_connection->isAutoCommit()) {
                $return = true;
            } else {
                $return = false;
            }
        }

        $this->in_transaction = false;

        return $return;
    }

    /**
     * Get all errors from "$this->errors".
     *
     * @return array|false
     *                     <p>false === on errors</p>
     */
    public function errors()
    {
        $errors = $this->debug->getErrors();

        return \count($errors) > 0 ? $errors : false;
    }

    /**
     * Escape: Use "mysqli_real_escape_string" and clean non UTF-8 chars + some extra optional stuff.
     *
     * @param mixed     $var           bool: convert into "integer"<br />
     *                                 int: int (don't change it)<br />
     *                                 float: float (don't change it)<br />
     *                                 null: null (don't change it)<br />
     *                                 array: run escape() for every key => value<br />
     *                                 string: run UTF8::cleanup() and mysqli_real_escape_string()<br />
     * @param bool      $stripe_non_utf8
     * @param bool      $html_entity_decode
     * @param bool|null $convert_array <strong>false</strong> => Keep the array.<br />
     *                                 <strong>true</strong> => Convert to string var1,var2,var3...<br />
     *                                 <strong>null</strong> => Convert the array into null, every time.
     *
     * @return mixed
     */
    public function escape($var = '', bool $stripe_non_utf8 = true, bool $html_entity_decode = false, $convert_array = false)
    {
        // [empty]
        if ($var === '') {
            return '';
        }

        // ''
        if ($var === "''") {
            return "''";
        }

        // check the type
        $type = \gettype($var);

        if ($type === 'object') {
            if ($var instanceof \DateTimeInterface) {
                $var = $var->format('Y-m-d H:i:s');
                $type = 'string';
            } elseif (\method_exists($var, '__toString')) {
                $var = (string) $var;
                $type = 'string';
            }
        }

        switch ($type) {
            case 'boolean':
                $var = (int) $var;

                break;

            case 'double':
            case 'integer':
                break;

            case 'string':
                if ($stripe_non_utf8) {
                    $var = UTF8::cleanup($var);
                }

                if ($html_entity_decode) {
                    $var = UTF8::html_entity_decode($var);
                }

                /** @noinspection PhpUsageOfSilenceOperatorInspection */
                $var = @\get_magic_quotes_gpc() ? \stripslashes($var) : $var;

                if (
                    $this->mysqli_link
                    &&
                    $this->mysqli_link instanceof \mysqli
                ) {
                    $var = \mysqli_real_escape_string($this->mysqli_link, $var);
                } elseif ($this->doctrine_connection && $this->isDoctrinePDOConnection()) {
                    $pdoConnection = $this->getDoctrinePDOConnection();
                    \assert($pdoConnection !== false);
                    $var = $pdoConnection->quote($var);
                    $var = \substr($var, 1, -1);
                }

                break;

            case 'array':
                if ($convert_array === null) {
                    if ($this->convert_null_to_empty_string) {
                        $var = "''";
                    } else {
                        $var = 'NULL';
                    }
                } else {
                    $varCleaned = [];
                    foreach ((array) $var as $key => $value) {
                        $key = $this->escape($key, $stripe_non_utf8, $html_entity_decode);
                        $value = $this->escape($value, $stripe_non_utf8, $html_entity_decode);

                        /** @noinspection OffsetOperationsInspection */
                        $varCleaned[$key] = $value;
                    }

                    if ($convert_array === true) {
                        $varCleaned = \implode(',', $varCleaned);

                        $var = $varCleaned;
                    } else {
                        $var = $varCleaned;
                    }
                }

                break;

            case 'NULL':
                if ($this->convert_null_to_empty_string) {
                    $var = "''";
                } else {
                    $var = 'NULL';
                }

                break;

            default:
                throw new \InvalidArgumentException(\sprintf('Not supported value "%s" of type %s.', \print_r($var, true), $type));

                break;

break; does not seem to be reachable.

        }

        return $var;
    }

    /**
     * Execute select/insert/update/delete sql-queries.
     *
     * @param string  $query    <p>sql-query</p>
     * @param bool    $useCache optional <p>use cache?</p>
     * @param int     $cacheTTL optional <p>cache-ttl in seconds</p>
     * @param DB|null $db       optional <p>the database connection</p>
     *
     * @throws QueryException
     *
     * @return mixed
     *               <ul>
     *               <li>"array" by "<b>SELECT</b>"-queries</li>
     *               <li>"int|string" (insert_id) by "<b>INSERT</b>"-queries</li>
     *               <li>"int" (affected_rows) by "<b>UPDATE / DELETE</b>"-queries</li>
     *               <li>"true" by e.g. "DROP"-queries</li>
     *               <li>"false" on error</li>
     *               </ul>
     */
    public static function execSQL(string $query, bool $useCache = false, int $cacheTTL = 3600, self $db = null)
    {
        // init
        $cacheKey = null;
        if (!$db) {
            $db = self::getInstance();
        }

        if ($useCache) {
            $cache = new Cache(null, null, false, $useCache);
            $cacheKey = 'sql-' . \md5($query);

            if (
                $cache->getCacheIsReady()
                &&
                $cache->existsItem($cacheKey)
            ) {
                return $cache->getItem($cacheKey);
            }
        } else {
            $cache = false;
        }

        $result = $db->query($query);

        if ($result instanceof Result) {
            $return = $result->fetchAllArray();

            // save into the cache
            if (
                $cacheKey !== null
                &&
                $useCache
                &&
                $cache instanceof Cache
                &&
                $cache->getCacheIsReady()
            ) {
                $cache->setItem($cacheKey, $return, $cacheTTL);
            }
        } else {
            $return = $result;
        }

        return $return;
    }

    /**
     * Get all table-names via "SHOW TABLES".
     *
     * @return array
     */
    public function getAllTables(): array
    {
        $query = 'SHOW TABLES';
        $result = $this->query($query);

        \assert($result instanceof Result);

        return $result->fetchAllArray();
    }

    /**
     * @return array
     */
    public function getConfig(): array
    {
        $config = [
            'hostname'   => $this->hostname,
            'username'   => $this->username,
            'password'   => $this->password,
            'port'       => $this->port,
            'database'   => $this->database,
            'socket'     => $this->socket,
            'charset'    => $this->charset,
            'cacert'     => $this->cacert,
            'clientcert' => $this->clientcert,
            'clientkey'  => $this->clientkey,
        ];

        if ($this->doctrine_connection instanceof \Doctrine\DBAL\Connection) {
            $config += $this->doctrine_connection->getParams();
        }

        return $config;
    }

    /**
     * @return Debug
     */
    public function getDebugger(): Debug
    {
        return $this->debug;
    }

    /**
     * @return \Doctrine\DBAL\Connection|null|null
     */
    public function getDoctrineConnection()
    {
        return $this->doctrine_connection;
    }

    /**
     * @return \Doctrine\DBAL\Driver\Connection|false
     */
    private function getDoctrinePDOConnection()

This method seems to be duplicated in your project.

    {
        if ($this->doctrine_connection) {
            $doctrineWrappedConnection = $this->doctrine_connection->getWrappedConnection();
            if ($doctrineWrappedConnection instanceof \Doctrine\DBAL\Driver\PDOConnection) {
                return $doctrineWrappedConnection;
            }
        }

        return false;
    }

    /**
     * Get errors from "$this->errors".
     *
     * @return array
     */
    public function getErrors(): array
    {
        return $this->debug->getErrors();
    }

    /**
     * @param string $hostname              <p>Hostname of the mysql server</p>
     * @param string $username              <p>Username for the mysql connection</p>
     * @param string $password              <p>Password for the mysql connection</p>
     * @param string $database              <p>Database for the mysql connection</p>
     * @param int    $port                  <p>default is (int)3306</p>
     * @param string $charset               <p>default is 'utf8' or 'utf8mb4' (if supported)</p>
     * @param bool   $exit_on_error         <p>Throw a 'Exception' when a query failed, otherwise it will return
     *                                      'false'. Use false to disable it.</p>
     * @param bool   $echo_on_error         <p>Echo the error if "checkForDev()" returns true.
     *                                      Use false to disable it.</p>
     * @param string $logger_class_name
     * @param string $logger_level          <p>'TRACE', 'DEBUG', 'INFO', 'WARN', 'ERROR', 'FATAL'</p>
     * @param array  $extra_config          <p>
     *                                      're_connect'    => bool<br>
     *                                      'session_to_db' => bool<br>
     *                                      'doctrine'      => \Doctrine\DBAL\Connection<br>
     *                                      'socket'        => string (path)<br>
     *                                      'flags'         => null|int<br>
     *                                      'ssl'           => bool<br>
     *                                      'clientkey'     => string (path)<br>
     *                                      'clientcert'    => string (path)<br>
     *                                      'cacert'        => string (path)<br>
     *                                      </p>
     *
     * @return self
     */
    public static function getInstance(
        string $hostname = '',
        string $username = '',
        string $password = '',
        string $database = '',
        $port = 3306,
        string $charset = 'utf8',
        bool $exit_on_error = true,
        bool $echo_on_error = true,
        string $logger_class_name = '',
        string $logger_level = '',
        array $extra_config = []
    ): self {
        /**
         * @var self[]
         */
        static $instance = [];

        /**
         * @var self|null
         */
        static $firstInstance = null;

        // fallback
        if (!$charset) {
            $charset = 'utf8';
        }

        if (
            '' . $hostname . $username . $password . $database . $port . $charset === '' . $port . $charset
            &&
            $firstInstance instanceof self
        ) {
            if (isset($extra_config['re_connect']) && $extra_config['re_connect'] === true) {
                $firstInstance->reconnect(true);
            }

            return $firstInstance;
        }

        $extra_config_string = '';
        foreach ($extra_config as $extra_config_key => $extra_config_value) {
            if (\is_object($extra_config_value)) {
                $extra_config_value_tmp = \spl_object_hash($extra_config_value);
            } else {
                $extra_config_value_tmp = (string) $extra_config_value;
            }
            $extra_config_string .= $extra_config_key . $extra_config_value_tmp;
        }

        $connection = \md5(
            $hostname . $username . $password . $database . $port . $charset . (int) $exit_on_error . (int) $echo_on_error . $logger_class_name . $logger_level . $extra_config_string
        );

        if (!isset($instance[$connection])) {
            $instance[$connection] = new self(
                $hostname,
                $username,
                $password,
                $database,
                $port,
                $charset,
                $exit_on_error,
                $echo_on_error,
                $logger_class_name,
                $logger_level,
                $extra_config
            );

            if ($firstInstance === null) {
                $firstInstance = $instance[$connection];
            }
        }

        if (isset($extra_config['re_connect']) && $extra_config['re_connect'] === true) {
            $instance[$connection]->reconnect(true);
        }

        return $instance[$connection];
    }

    /**
     * @param \Doctrine\DBAL\Connection $doctrine
     * @param string                    $charset       <p>default is 'utf8' or 'utf8mb4' (if supported)</p>
     * @param bool                      $exit_on_error <p>Throw a 'Exception' when a query failed, otherwise it will
     *                                                 return 'false'. Use false to disable it.</p>
     * @param bool                      $echo_on_error <p>Echo the error if "checkForDev()" returns true.
     *                                                 Use false to disable it.</p>
     * @param string                    $logger_class_name
     * @param string                    $logger_level  <p>'TRACE', 'DEBUG', 'INFO', 'WARN', 'ERROR', 'FATAL'</p>
     * @param array                     $extra_config  <p>
     *                                                 're_connect'    => bool<br>
     *                                                 'session_to_db' => bool<br>
     *                                                 'socket'        => string (path)<br>
     *                                                 'flags'         => null|int<br>
     *                                                 'ssl'           => bool<br>
     *                                                 'clientkey'     => string (path)<br>
     *                                                 'clientcert'    => string (path)<br>
     *                                                 'cacert'        => string (path)<br>
     *                                                 </p>
     *
     * @return self
     */
    public static function getInstanceDoctrineHelper(
        \Doctrine\DBAL\Connection $doctrine,
        string $charset = 'utf8',
        bool $exit_on_error = true,
        bool $echo_on_error = true,
        string $logger_class_name = '',
        string $logger_level = '',
        array $extra_config = []
    ): self {
        $extra_config['doctrine'] = $doctrine;

        return self::getInstance(
            '',
            '',
            '',
            '',
            3306,
            $charset,
            $exit_on_error,
            $echo_on_error,
            $logger_class_name,
            $logger_level,
            $extra_config
        );
    }

    /**
     * Get the mysqli-link (link identifier returned by mysqli-connect).
     *
     * @return \mysqli|null
     */
    public function getLink()
    {
        return $this->mysqli_link;
    }

    /**
     * Get the current charset.
     *
     * @return string
     */
    public function get_charset(): string
    {
        return $this->charset;
    }

    /**
     * Check if we are in a transaction.
     *
     * @return bool
     */
    public function inTransaction(): bool
    {
        return $this->in_transaction;
    }

    /**
     * Execute a "insert"-query.
     *
     * @param string      $table
     * @param array       $data
     * @param string|null $databaseName <p>Use <strong>null</strong> if you will use the current database.</p>
     *
     * @throws QueryException
     *
     * @return false|int|string
     *                   <p>false on error</p>
     */
    public function insert(string $table, array $data = [], string $databaseName = null)
    {
        // init
        $table = \trim($table);

        if ($table === '') {
            $this->debug->displayError('Invalid table name, table name in empty.', false);

            return false;
        }

        if (\count($data) === 0) {
            $this->debug->displayError('Invalid data for INSERT, data is empty.', false);

            return false;
        }

        $SET = $this->_parseArrayPair($data);

        if ($databaseName) {

The expression $databaseName of type null|string is loosely compared to true; this is ambiguous if the string can be empty. You might want to explicitly use !== null instead.

            $databaseName = $this->quote_string(\trim($databaseName)) . '.';
        }

        $sql = 'INSERT INTO ' . $databaseName . $this->quote_string($table) . " SET ${SET}";

        $return = $this->query($sql);
        if ($return === false) {
            return false;
        }

        \assert(\is_int($return) || \is_string($return));

        return $return;
    }

    /**
     * Returns the auto generated id used in the last query.
     *
     * @return false|int|string
     */
    public function insert_id()
    {
        if ($this->mysqli_link) {
            return \mysqli_insert_id($this->mysqli_link);
        }

        $doctrinePDOConnection = $this->getDoctrinePDOConnection();
        if ($doctrinePDOConnection) {
            return $doctrinePDOConnection->lastInsertId();
        }

        return false;
    }

    /**
     * @return bool
     */
    public function isDoctrineMySQLiConnection(): bool
    {
        if ($this->doctrine_connection) {
            $doctrineWrappedConnection = $this->doctrine_connection->getWrappedConnection();
            if ($doctrineWrappedConnection instanceof \Doctrine\DBAL\Driver\Mysqli\MysqliConnection) {
                return true;
            }
        }

        return false;
    }

    /**
     * @return bool
     */
    public function isDoctrinePDOConnection(): bool

This method seems to be duplicated in your project.

    {
        if ($this->doctrine_connection) {
            $doctrineWrappedConnection = $this->doctrine_connection->getWrappedConnection();
            if ($doctrineWrappedConnection instanceof \Doctrine\DBAL\Driver\PDOConnection) {
                return true;
            }
        }

        return false;
    }

    /**
     * Check if db-connection is ready.
     *
     * @return bool
     */
    public function isReady(): bool
    {
        return $this->connected ? true : false;
    }

    /**
     * Get the last sql-error.
     *
     * @return false|string
     *                      <p>false === there was no error</p>
     */
    public function lastError()
    {
        $errors = $this->debug->getErrors();

        return \count($errors) > 0 ? \end($errors) : false;
    }

    /**
     * Execute a sql-multi-query.
     *
     * @param string $sql
     *
     * @throws QueryException
     *
     * @return bool|Result[]
     *                        <ul>
     *                        <li>"Result"-Array by "<b>SELECT</b>"-queries</li>
     *                        <li>"bool" by only "<b>INSERT</b>"-queries</li>
     *                        <li>"bool" by only (affected_rows) by "<b>UPDATE / DELETE</b>"-queries</li>
     *                        <li>"bool" by only by e.g. "DROP"-queries</li>
     *                        </ul>
     */
    public function multi_query(string $sql)
    {
        if (!$this->isReady()) {
            return false;
        }

        if (!$sql || $sql === '') {
            $this->debug->displayError('Can not execute an empty query.', false);

            return false;
        }

        if ($this->doctrine_connection && $this->isDoctrinePDOConnection()) {
            $query_start_time = \microtime(true);
            $queryException = null;
            $query_result_doctrine = false;

            try {
                $query_result_doctrine = $this->doctrine_connection->prepare($sql);
                $resultTmp = $query_result_doctrine->execute();
                $mysqli_field_count = $query_result_doctrine->columnCount();
            } catch (\Exception $e) {
                $resultTmp = false;
                $mysqli_field_count = null;

                $queryException = $e;
            }

            $query_duration = \microtime(true) - $query_start_time;

            $this->debug->logQuery($sql, $query_duration, 0);

            $returnTheResult = false;
            $result = [];

            if ($resultTmp) {
                if ($mysqli_field_count) {

The expression $mysqli_field_count of type integer|null is loosely compared to true; this is ambiguous if the integer can be zero. You might want to explicitly use !== null instead.

                    if (
                        $query_result_doctrine
                        &&
                        $query_result_doctrine instanceof \Doctrine\DBAL\Statement
                    ) {
                        $result = $query_result_doctrine;
                    }
                } else {
                    $result = $resultTmp;
                }

                if (
                    $result instanceof \Doctrine\DBAL\Statement
                    &&
                    $result->columnCount() > 0
                ) {
                    $returnTheResult = true;

                    // return query result object
                    $result = [new Result($sql, $result)];
                } else {
                    $result = [$result];
                }
            } else {

                // log the error query
                $this->debug->logQuery($sql, $query_duration, 0, true);

                if (
                    isset($queryException)
                    &&
                    $queryException instanceof \Doctrine\DBAL\Query\QueryException
                ) {
                    return $this->queryErrorHandling($queryException->getMessage(), $queryException->getCode(), $sql, false, true);
                }
            }
        } elseif ($this->mysqli_link) {
            $query_start_time = \microtime(true);
            $resultTmp = \mysqli_multi_query($this->mysqli_link, $sql);
            $query_duration = \microtime(true) - $query_start_time;

            $this->debug->logQuery($sql, $query_duration, 0);

            $returnTheResult = false;
            $result = [];

            if ($resultTmp) {
                do {
                    $resultTmpInner = \mysqli_store_result($this->mysqli_link);

                    if ($resultTmpInner instanceof \mysqli_result) {
                        $returnTheResult = true;
                        $result[] = new Result($sql, $resultTmpInner);
                    } elseif (\mysqli_errno($this->mysqli_link)) {
                        $result[] = false;
                    } else {
                        $result[] = true;
                    }
                } while (\mysqli_more_results($this->mysqli_link) ? \mysqli_next_result($this->mysqli_link) : false);
            } else {

                // log the error query
                $this->debug->logQuery($sql, $query_duration, 0, true);

                return $this->queryErrorHandling(\mysqli_error($this->mysqli_link), \mysqli_errno($this->mysqli_link), $sql, false, true);
            }
        } else {

            // log the error query
            $this->debug->logQuery($sql, 0, 0, true);

            return $this->queryErrorHandling('no database connection', 1, $sql, false, true);
        }

        // return the result only if there was a "SELECT"-query
        if ($returnTheResult) {
            return $result;
        }

        if (
            \count($result) > 0
            &&
            !\in_array(false, $result, true)
        ) {
            return true;
        }

        return false;
    }

    /**
     * Count number of rows found matching a specific query.
     *
     * @param string $query
     *
     * @return int
     */
    public function num_rows(string $query): int
    {
        $check = $this->query($query);

        if (
            $check === false
            ||
            !$check instanceof Result
        ) {
            return 0;
        }

        return $check->num_rows;
    }

    /**
     * Pings a server connection, or tries to reconnect
     * if the connection has gone down.
     *
     * @return bool
     */
    public function ping(): bool
    {
        if (!$this->connected) {
            return false;
        }

        if ($this->doctrine_connection && $this->isDoctrinePDOConnection()) {
            return $this->doctrine_connection->ping();
        }

        if (
            $this->mysqli_link
            &&
            $this->mysqli_link instanceof \mysqli
        ) {
            return \mysqli_ping($this->mysqli_link);
        }

        return false;
    }

    /**
     * Get a new "Prepare"-Object for your sql-query.
     *
     * @param string $query
     *
     * @return Prepare
     */
    public function prepare(string $query): Prepare
    {
        return new Prepare($this, $query);
    }

    /**
     * Execute a sql-query and return the result-array for select-statements.
     *
     * @param string $query
     *
     * @throws \Exception
     *
     * @return mixed
     *
     * @deprecated
     */
    public static function qry(string $query)

The parameter $query is not used and could be removed.

    {
        $db = self::getInstance();

        $args = \func_get_args();
        /** @noinspection SuspiciousAssignmentsInspection */
        $query = \array_shift($args);
        $query = \str_replace('?', '%s', $query);
        $args = \array_map(
            [
                $db,
                'escape',
            ],
            $args
        );
        \array_unshift($args, $query);
        $query = \sprintf(...$args);
        $result = $db->query($query);

        if ($result instanceof Result) {
            return $result->fetchAllArray();
        }

        return $result;
    }

    /**
     * Execute a sql-query.
     *
     * example:
     * <code>
     * $sql = "INSERT INTO TABLE_NAME_HERE
     *   SET
     *     foo = :foo,
     *     bar = :bar
     * ";
     * $insert_id = $db->query(
     *   $sql,
     *   [
     *     'foo' => 1.1,
     *     'bar' => 1,
     *   ]
     * );
     * </code>
     *
     * @param string     $sql               <p>The sql query-string.</p>
     * @param array|bool $params            <p>
     *                                      "array" of sql-query-parameters<br/>
     *                                      "false" if you don't need any parameter (default)<br/>
     *                                      </p>
     *
     * @throws QueryException
     *
     * @return bool|int|Result|string
     *                                      <p>
     *                                      "Result" by "<b>SELECT</b>"-queries<br />
     *                                      "int|string" (insert_id) by "<b>INSERT / REPLACE</b>"-queries<br />
     *                                      "int" (affected_rows) by "<b>UPDATE / DELETE</b>"-queries<br />
     *                                      "true" by e.g. "DROP"-queries<br />
     *                                      "false" on error
     *                                      </p>
     */
    public function query(string $sql = '', $params = false)
    {
        if (!$this->isReady()) {
            return false;
        }

        if ($sql === '') {
            $this->debug->displayError('Can not execute an empty query.', false);

            return false;
        }

        if (
            $params !== false
            &&
            \is_array($params)
            &&
            \count($params) > 0
        ) {
            $parseQueryParams = $this->_parseQueryParams($sql, $params);
            $parseQueryParamsByName = $this->_parseQueryParamsByName($parseQueryParams['sql'], $parseQueryParams['params']);
            $sql = $parseQueryParamsByName['sql'];
        }

        // DEBUG
        // var_dump($params);
        // echo $sql . "\n";

        $query_start_time = \microtime(true);
        $queryException = null;
        $query_result_doctrine = false;

        if ($this->doctrine_connection) {
            try {
                $query_result_doctrine = $this->doctrine_connection->prepare($sql);
                $query_result = $query_result_doctrine->execute();
                $mysqli_field_count = $query_result_doctrine->columnCount();
            } catch (\Exception $e) {
                $query_result = false;
                $mysqli_field_count = null;

                $queryException = $e;
            }
        } elseif ($this->mysqli_link) {
            $query_result = \mysqli_real_query($this->mysqli_link, $sql);
            $mysqli_field_count = \mysqli_field_count($this->mysqli_link);
        } else {
            $query_result = false;
            $mysqli_field_count = null;

            $queryException = new DBConnectException('no mysql connection');
        }

        $query_duration = \microtime(true) - $query_start_time;

        $this->query_count++;

        if ($mysqli_field_count) {

The expression $mysqli_field_count of type integer|null is loosely compared to true; this is ambiguous if the integer can be zero. You might want to explicitly use !== null instead.

            if ($this->doctrine_connection) {
                $result = false;
                if (
                    $query_result_doctrine
                    &&
                    $query_result_doctrine instanceof \Doctrine\DBAL\Statement
                ) {
                    $result = $query_result_doctrine;
                }
            } elseif ($this->mysqli_link) {
                $result = \mysqli_store_result($this->mysqli_link);
            } else {
                $result = false;
            }
        } else {
            $result = $query_result;
        }

        if (
            $result instanceof \Doctrine\DBAL\Statement
            &&
            $result->columnCount() > 0
        ) {

            // log the select query
            $this->debug->logQuery($sql, $query_duration, $mysqli_field_count);

            // return query result object
            return new Result($sql, $result);
        }

        if ($result instanceof \mysqli_result) {

            // log the select query
            $this->debug->logQuery($sql, $query_duration, $mysqli_field_count);

            // return query result object
            return new Result($sql, $result);
        }

        if ($query_result) {

            // "INSERT" || "REPLACE"
            if (\preg_match('/^\s*?(?:INSERT|REPLACE)\s+/i', $sql)) {
                $insert_id = $this->insert_id();

                $this->debug->logQuery($sql, $query_duration, $insert_id);

                return $insert_id;
            }

            // "UPDATE" || "DELETE"
            if (\preg_match('/^\s*?(?:UPDATE|DELETE)\s+/i', $sql)) {
                if ($this->mysqli_link) {
                    $this->affected_rows = $this->affected_rows();
                } elseif ($query_result_doctrine) {
                    $this->affected_rows = $query_result_doctrine->rowCount();
                }

                $this->debug->logQuery($sql, $query_duration, $this->affected_rows);

                return $this->affected_rows;
            }

            // log the ? query
            $this->debug->logQuery($sql, $query_duration, 0);

            return true;
        }

        // log the error query
        $this->debug->logQuery($sql, $query_duration, 0, true);

        if ($queryException) {
            return $this->queryErrorHandling($queryException->getMessage(), $queryException->getCode(), $sql, $params);
        }

        if ($this->mysqli_link) {
            return $this->queryErrorHandling(\mysqli_error($this->mysqli_link), \mysqli_errno($this->mysqli_link), $sql, $params);
        }

        return false;
    }

    /**
     * Error-handling for the sql-query.
     *
     * @param string     $errorMessage
     * @param int        $errorNumber
     * @param string     $sql
     * @param array|bool $sqlParams <p>false if there wasn't any parameter</p>
     * @param bool       $sqlMultiQuery
     *
     * @throws QueryException
     * @throws DBGoneAwayException
     *
     * @return false|mixed
     */
    private function queryErrorHandling(string $errorMessage, int $errorNumber, string $sql, $sqlParams = false, bool $sqlMultiQuery = false)
    {
        if (
            $errorMessage === 'DB server has gone away'
            ||
            $errorMessage === 'MySQL server has gone away'
            ||
            $errorNumber === 2006
        ) {
            static $RECONNECT_COUNTER;

            // exit if we have more then 3 "DB server has gone away"-errors
            if ($RECONNECT_COUNTER > 3) {
                $this->debug->mailToAdmin('DB-Fatal-Error', $errorMessage . '(' . $errorNumber . ') ' . ":\n<br />" . $sql, 5);

                throw new DBGoneAwayException($errorMessage);
            }

            $this->debug->mailToAdmin('DB-Error', $errorMessage . '(' . $errorNumber . ') ' . ":\n<br />" . $sql);

            // reconnect
            $RECONNECT_COUNTER++;
            $this->reconnect(true);

            // re-run the current (non multi) query
            if (!$sqlMultiQuery) {
                return $this->query($sql, $sqlParams);
            }

            return false;
        }

        $this->debug->mailToAdmin('SQL-Error', $errorMessage . '(' . $errorNumber . ') ' . ":\n<br />" . $sql);

        $force_exception_after_error = null; // auto
        if ($this->in_transaction) {
            $force_exception_after_error = false;
        }
        // this query returned an error, we must display it (only for dev) !!!

        $this->debug->displayError($errorMessage . '(' . $errorNumber . ') ' . ' | ' . $sql, $force_exception_after_error);

        return false;
    }

    /**
     * Quote && Escape e.g. a table name string.
     *
     * @param mixed $str
     *
     * @return string
     */
    public function quote_string($str): string
    {
        $str = \str_replace(
            '`',
            '``',
            \trim(
                (string) $this->escape($str, false),
                '`'
            )
        );

        return '`' . $str . '`';
    }

    /**
     * Reconnect to the MySQL-Server.
     *
     * @param bool $checkViaPing
     *
     * @return bool
     */
    public function reconnect(bool $checkViaPing = false): bool
    {
        $ping = false;
        if ($checkViaPing) {
            $ping = $this->ping();
        }

        if (!$ping) {
            $this->connected = false;
            $this->connect();
        }

        return $this->isReady();
    }

    /**
     * Execute a "replace"-query.
     *
     * @param string      $table
     * @param array       $data
     * @param string|null $databaseName <p>Use <strong>null</strong> if you will use the current database.</p>
     *
     * @throws QueryException
     *
     * @return false|int
     *                   <p>false on error</p>
     */
    public function replace(string $table, array $data = [], string $databaseName = null)
    {
        // init
        $table = \trim($table);

        if ($table === '') {
            $this->debug->displayError('Invalid table name, table name in empty.', false);

            return false;
        }

        if (\count($data) === 0) {
            $this->debug->displayError('Invalid data for REPLACE, data is empty.', false);

            return false;
        }

        // extracting column names
        $columns = \array_keys($data);
        foreach ($columns as $k => $_key) {
            $columns[$k] = $this->quote_string($_key);
        }

        $columns = \implode(',', $columns);

        // extracting values
        foreach ($data as $k => $_value) {
            $data[$k] = $this->secure($_value);
        }
        $values = \implode(',', $data);

        if ($databaseName) {

The expression $databaseName of type null|string is loosely compared to true; this is ambiguous if the string can be empty. You might want to explicitly use !== null instead.

            $databaseName = $this->quote_string(\trim($databaseName)) . '.';
        }

        $sql = 'REPLACE INTO ' . $databaseName . $this->quote_string($table) . " (${columns}) VALUES (${values})";

        $return = $this->query($sql);
        \assert(\is_int($return) || $return === false);

        return $return;
    }

    /**
     * Rollback in a transaction and end the transaction.
     *
     * @return bool
     *              <p>bool true on success, false otherwise.</p>
     */
    public function rollback(): bool

This method seems to be duplicated in your project.

    {
        if (!$this->in_transaction) {
            $this->debug->displayError('Error: mysql server is not in transaction!', false);

            return false;
        }

        // init
        $return = false;

        if ($this->mysqli_link) {
            $return = \mysqli_rollback($this->mysqli_link);
            \mysqli_autocommit($this->mysqli_link, true);
        } elseif ($this->doctrine_connection && $this->isDoctrinePDOConnection()) {
            $this->doctrine_connection->rollBack();
            $this->doctrine_connection->setAutoCommit(true);

            if ($this->doctrine_connection->isAutoCommit()) {
                $return = true;
            } else {
                $return = false;
            }
        }

        $this->in_transaction = false;

        return $return;
    }

    /**
     * Try to secure a variable, so can you use it in sql-queries.
     *
     * <p>
     * <strong>int:</strong> (also strings that contains only an int-value)<br />
     * 1. parse into "int"
     * </p><br />
     *
     * <p>
     * <strong>float:</strong><br />
     * 1. return "float"
     * </p><br />
     *
     * <p>
     * <strong>string:</strong><br />
     * 1. check if the string isn't a default mysql-time-function e.g. 'CURDATE()'<br />
     * 2. trim '<br />
     * 3. escape the string (and remove non utf-8 chars)<br />
     * 4. trim ' again (because we maybe removed some chars)<br />
     * 5. add ' around the new string<br />
     * </p><br />
     *
     * <p>
     * <strong>array:</strong><br />
     * 1. return null
     * </p><br />
     *
     * <p>
     * <strong>object:</strong><br />
     * 1. return false
     * </p><br />
     *
     * <p>
     * <strong>null:</strong><br />
     * 1. return null
     * </p>
     *
     * @param mixed     $var
     * @param bool|null $convert_array <strong>false</strong> => Keep the array.<br />
     *                                 <strong>true</strong> => Convert to string var1,var2,var3...<br />
     *                                 <strong>null</strong> => Convert the array into null, every time.
     *
     * @return mixed
     */
    public function secure($var, $convert_array = true)
    {
        if (\is_array($var)) {
            if ($convert_array === null) {
                if ($this->convert_null_to_empty_string) {
                    $var = "''";
                } else {
                    $var = 'NULL';
                }
            } else {
                $varCleaned = [];
                foreach ((array) $var as $key => $value) {
                    $key = $this->escape($key, false, false, $convert_array);
                    $value = $this->secure($value);

                    /** @noinspection OffsetOperationsInspection */
                    $varCleaned[$key] = $value;
                }

                if ($convert_array === true) {
                    $varCleaned = \implode(',', $varCleaned);

                    $var = $varCleaned;
                } else {
                    $var = $varCleaned;
                }
            }

            return $var;
        }

        if ($var === '') {
            return "''";
        }

        if ($var === "''") {
            return "''";
        }

        if ($var === null) {
            if ($this->convert_null_to_empty_string) {
                return "''";
            }

            return 'NULL';
        }

        if (\in_array($var, $this->mysqlDefaultTimeFunctions, true)) {
            return $var;
        }

        if (\is_string($var)) {
            $var = \trim($var, "'");
        }

        $var = $this->escape($var, false, false, null);

        if (\is_string($var)) {
            $var = "'" . \trim($var, "'") . "'";
        }

        return $var;
    }

    /**
     * Execute a "select"-query.
     *
     * @param string       $table
     * @param array|string $where
     * @param string|null  $databaseName <p>Use <strong>null</strong> if you will use the current database.</p>
     *
     * @throws QueryException
     *
     * @return false|Result
     *                      <p>false on error</p>
     */
    public function select(string $table, $where = '1=1', string $databaseName = null)

This method seems to be duplicated in your project.

    {
        // init
        $table = \trim($table);

        if ($table === '') {
            $this->debug->displayError('Invalid table name, table name in empty.', false);

            return false;
        }

        if (\is_string($where)) {
            $WHERE = $this->escape($where, false);
        } elseif (\is_array($where)) {
            $WHERE = $this->_parseArrayPair($where, 'AND');
        } else {
            $WHERE = '';
        }

        if ($databaseName) {

The expression $databaseName of type null|string is loosely compared to true; this is ambiguous if the string can be empty. You might want to explicitly use !== null instead.

            $databaseName = $this->quote_string(\trim($databaseName)) . '.';
        }

        $sql = 'SELECT * FROM ' . $databaseName . $this->quote_string($table) . " WHERE (${WHERE})";

        $return = $this->query($sql);
        \assert($return instanceof Result || $return === false);

        return $return;
    }

    /**
     * Selects a different database than the one specified on construction.
     *
     * @param string $database <p>Database name to switch to.</p>
     *
     * @return bool
     *              <p>bool true on success, false otherwise.</p>
     */
    public function select_db(string $database): bool
    {
        if (!$this->isReady()) {
            return false;
        }

        if ($this->mysqli_link) {
            return \mysqli_select_db($this->mysqli_link, $database);
        }

        if ($this->doctrine_connection && $this->isDoctrinePDOConnection()) {
            $return = $this->query('use :database', ['database' => $database]);
            \assert(\is_bool($return));

            return $return;
        }

        return false;
    }

    /**
     * @param array  $extra_config          <p>
     *                                      'session_to_db' => bool<br>
     *                                      'doctrine'      => \Doctrine\DBAL\Connection<br>
     *                                      'socket'        => string (path)<br>
     *                                      'flags'         => null|int<br>
     *                                      'ssl'           => bool<br>
     *                                      'clientkey'     => string (path)<br>
     *                                      'clientcert'    => string (path)<br>
     *                                      'cacert'        => string (path)<br>
     *                                      </p>
     */
    public function setConfigExtra(array $extra_config)
    {
        if (isset($extra_config['session_to_db'])) {
            $this->session_to_db = (bool) $extra_config['session_to_db'];
        }

        if (isset($extra_config['doctrine'])) {
            if ($extra_config['doctrine'] instanceof \Doctrine\DBAL\Connection) {
                $this->doctrine_connection = $extra_config['doctrine'];
            } else {
                throw new DBConnectException('Error "doctrine"-connection is not valid');
            }
        }

        if (isset($extra_config['socket'])) {
            $this->socket = $extra_config['socket'];
        }

        if (isset($extra_config['flags'])) {
            $this->flags = $extra_config['flags'];
        }

        if (isset($extra_config['ssl'])) {
            $this->ssl = $extra_config['ssl'];
        }

        if (isset($extra_config['clientkey'])) {
            $this->clientkey = $extra_config['clientkey'];
        }

        if (isset($extra_config['clientcert'])) {
            $this->clientcert = $extra_config['clientcert'];
        }

        if (isset($extra_config['cacert'])) {
            $this->cacert = $extra_config['cacert'];
        }
    }

    /**
     * Set the current charset.
     *
     * @param string $charset
     *
     * @return bool
     */
    public function set_charset(string $charset): bool
    {
        $charsetLower = \strtolower($charset);
        if ($charsetLower === 'utf8' || $charsetLower === 'utf-8') {
            $charset = 'utf8';
        }
        if ($charset === 'utf8' && Helper::isUtf8mb4Supported($this)) {
            $charset = 'utf8mb4';
        }

        $this->charset = $charset;

        if (
            $this->mysqli_link
            &&
            $this->mysqli_link instanceof \mysqli
        ) {
            $return = \mysqli_set_charset($this->mysqli_link, $charset);

            /** @noinspection PhpUsageOfSilenceOperatorInspection */
            @\mysqli_query($this->mysqli_link, 'SET CHARACTER SET ' . $charset);
            /** @noinspection PhpUsageOfSilenceOperatorInspection */
            @\mysqli_query($this->mysqli_link, "SET NAMES '" . $charset . "'");

It seems like you do not handle an error condition here. This can introduce security issues, and is generally not recommended.

        } elseif ($this->doctrine_connection && $this->isDoctrinePDOConnection()) {
            $doctrineWrappedConnection = $this->getDoctrinePDOConnection();
            if (!$doctrineWrappedConnection instanceof Connection) {
                return false;
            }

            /** @noinspection PhpUsageOfSilenceOperatorInspection */
            @$doctrineWrappedConnection->exec('SET CHARACTER SET ' . $charset);

It seems like you do not handle an error condition here. This can introduce security issues, and is generally not recommended.

            /** @noinspection PhpUsageOfSilenceOperatorInspection */
            @$doctrineWrappedConnection->exec("SET NAMES '" . $charset . "'");

It seems like you do not handle an error condition here. This can introduce security issues, and is generally not recommended.

            $return = true;
        } else {
            $return = false;
        }

        return $return;
    }

    /**
     * Set the option to convert null to "''" (empty string).
     *
     * Used in secure() => select(), insert(), update(), delete()
     *
     * @deprecated It's not recommended to convert NULL into an empty string!
     *
     * @param bool $bool
     *
     * @return self
     */
    public function set_convert_null_to_empty_string(bool $bool): self
    {
        $this->convert_null_to_empty_string = $bool;

        return $this;
    }

    /**
     * Enables or disables internal report functions
     *
     * @see http://php.net/manual/en/function.mysqli-report.php
     *
     * @param int $flags <p>
     *                   <table>
     *                   Supported flags
     *                   <tr valign="top">
     *                   <td>Name</td>
     *                   <td>Description</td>
     *                   </tr>
     *                   <tr valign="top">
     *                   <td><b>MYSQLI_REPORT_OFF</b></td>
     *                   <td>Turns reporting off</td>
     *                   </tr>
     *                   <tr valign="top">
     *                   <td><b>MYSQLI_REPORT_ERROR</b></td>
     *                   <td>Report errors from mysqli function calls</td>
     *                   </tr>
     *                   <tr valign="top">
     *                   <td><b>MYSQLI_REPORT_STRICT</b></td>
     *                   <td>
     *                   Throw <b>mysqli_sql_exception</b> for errors
     *                   instead of warnings
     *                   </td>
     *                   </tr>
     *                   <tr valign="top">
     *                   <td><b>MYSQLI_REPORT_INDEX</b></td>
     *                   <td>Report if no index or bad index was used in a query</td>
     *                   </tr>
     *                   <tr valign="top">
     *                   <td><b>MYSQLI_REPORT_ALL</b></td>
     *                   <td>Set all options (report all)</td>
     *                   </tr>
     *                   </table>
     *                   </p>
     *
     * @return bool
     */
    public function set_mysqli_report(int $flags): bool
    {
        if (
            $this->mysqli_link
            &&
            $this->mysqli_link instanceof \mysqli
        ) {
            return \mysqli_report($flags);
        }

        return false;
    }

    /**
     * Show config errors by throw exceptions.
     *
     * @throws \InvalidArgumentException
     *
     * @return bool
     */
    public function showConfigError(): bool
    {
        // check if a doctrine connection is already open, first
        if (
            $this->doctrine_connection
            &&
            $this->doctrine_connection->isConnected()
        ) {
            return true;
        }

        if (
            !$this->hostname
            ||
            !$this->username
            ||
            !$this->database
        ) {
            if (!$this->hostname) {
                throw new \InvalidArgumentException('no-sql-hostname');
            }

            if (!$this->username) {
                throw new \InvalidArgumentException('no-sql-username');
            }

            if (!$this->database) {
                throw new \InvalidArgumentException('no-sql-database');
            }

            return false;
        }

        return true;
    }

    /**
     * alias: "beginTransaction()"
     */
    public function startTransaction(): bool
    {
        return $this->beginTransaction();
    }

    /**
     * Determine if database table exists
     *
     * @param string $table
     *
     * @return bool
     */
    public function table_exists(string $table): bool
    {
        $check = $this->query('SELECT 1 FROM ' . $this->quote_string($table));

        return $check !== false
               &&
               $check instanceof Result
               &&
               $check->num_rows > 0;
    }

    /**
     * Execute a callback inside a transaction.
     *
     * @param \Closure $callback <p>The callback to run inside the transaction, if it's throws an "Exception" or if it's
     *                           returns "false", all SQL-statements in the callback will be rollbacked.</p>
     *
     * @return bool
     *              <p>bool true on success, false otherwise.</p>
     */
    public function transact($callback): bool
    {
        try {
            $beginTransaction = $this->beginTransaction();
            if (!$beginTransaction) {
                $this->debug->displayError('Error: transact -> can not start transaction!', false);

                return false;
            }

            $result = $callback($this);
            if ($result === false) {
                /** @noinspection ThrowRawExceptionInspection */
                throw new \Exception('call_user_func [' . \print_r($callback, true) . '] === false');
            }

            return $this->commit();
        } catch (\Exception $e) {
            $this->rollback();

            return false;
        }
    }

    /**
     * Execute a "update"-query.
     *
     * @param string       $table
     * @param array        $data
     * @param array|string $where
     * @param string|null  $databaseName <p>Use <strong>null</strong> if you will use the current database.</p>
     *
     * @throws QueryException
     *
     * @return false|int
     *                   <p>false on error</p>
     */
    public function update(string $table, array $data = [], $where = '1=1', string $databaseName = null)
    {
        // init
        $table = \trim($table);

        if ($table === '') {
            $this->debug->displayError('Invalid table name, table name in empty.', false);

            return false;
        }

        if (\count($data) === 0) {
            $this->debug->displayError('Invalid data for UPDATE, data is empty.', false);

            return false;
        }

        // DEBUG
        //var_dump($data);

        $SET = $this->_parseArrayPair($data);

        // DEBUG
        //var_dump($SET);

        if (\is_string($where)) {
            $WHERE = $this->escape($where, false);
        } elseif (\is_array($where)) {
            $WHERE = $this->_parseArrayPair($where, 'AND');
        } else {
            $WHERE = '';
        }

        if ($databaseName) {

The expression $databaseName of type null|string is loosely compared to true; this is ambiguous if the string can be empty. You might want to explicitly use !== null instead.

            $databaseName = $this->quote_string(\trim($databaseName)) . '.';
        }

        $sql = 'UPDATE ' . $databaseName . $this->quote_string($table) . " SET ${SET} WHERE (${WHERE})";

        $return = $this->query($sql);
        \assert(\is_int($return) || $return === false);

        return $return;
    }
}