Complex classes like Db often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Db, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 22 | class Db |
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| 23 | { |
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| 24 | /** |
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| 25 | * Database handle/connection. |
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| 26 | * |
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| 27 | * @var PDO |
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| 28 | */ |
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| 29 | protected $pdo; |
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| 30 | |||
| 31 | /** |
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| 32 | * @var string |
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| 33 | */ |
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| 34 | protected $dsn; |
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| 35 | |||
| 36 | /** |
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| 37 | * @var string |
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| 38 | */ |
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| 39 | protected $username; |
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| 40 | |||
| 41 | /** |
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| 42 | * @var string |
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| 43 | */ |
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| 44 | protected $password; |
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| 45 | |||
| 46 | /** |
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| 47 | * @var array |
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| 48 | */ |
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| 49 | protected $options; |
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| 50 | |||
| 51 | /** |
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| 52 | * @var bool |
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| 53 | */ |
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| 54 | protected $hasActiveTransaction = false; |
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| 55 | |||
| 56 | /** |
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| 57 | * @var PdoFactoryInterface |
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| 58 | */ |
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| 59 | private $pdoFactory; |
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| 60 | |||
| 61 | /** |
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| 62 | * Constructor. |
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| 63 | * |
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| 64 | * @param string|PDO $hostDsnOrPdo A MySQL host, a dsn or an existing PDO instance. |
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| 65 | * @param string|null $username |
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| 66 | * @param string|null $password |
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| 67 | * @param string|null $database |
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| 68 | * @param array $options |
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| 69 | * @param PdoFactoryInterface $pdoFactory |
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| 70 | * |
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| 71 | * @deprecated The signature of the constructor will change in version 1.0.0 and accept |
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| 72 | * only a PDO dsn string as first parameter dropping support to inject a PDO instance or host string |
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| 73 | */ |
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| 74 | 28 | public function __construct( |
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| 75 | $hostDsnOrPdo, |
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| 76 | $username = null, |
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| 77 | $password = null, |
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| 78 | $database = null, |
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| 79 | array $options = [], |
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| 80 | PdoFactoryInterface $pdoFactory = null |
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| 81 | ) { |
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| 82 | 28 | if ($hostDsnOrPdo instanceof PDO) { |
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| 83 | 28 | @trigger_error( |
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| 84 | 'Support to pass a PDO instance to the constructor is deprecated and will be removed in version 1.0.0.' |
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| 85 | 28 | . ' You need to pass in a PDO dsn in the future as first parameter.', |
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| 86 | 28 | E_USER_DEPRECATED |
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| 87 | ); |
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| 88 | |||
| 89 | 28 | $this->pdo = $hostDsnOrPdo; |
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| 90 | 4 | } elseif (strpos($hostDsnOrPdo, ':') !== false) { |
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| 91 | 3 | $this->dsn = $hostDsnOrPdo; |
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| 92 | } else { |
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| 93 | 1 | @trigger_error( |
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| 94 | 'Support to pass a host and database to the constructor is deprecated and will be removed in version ' |
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| 95 | 1 | . '1.0.0. You need to pass in a PDO dsn in the future as first parameter.', |
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| 96 | 1 | E_USER_DEPRECATED |
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| 97 | ); |
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| 98 | 1 | $this->dsn = "mysql:host={$hostDsnOrPdo}" . ($database ? ";dbname={$database}" : ''); |
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| 99 | } |
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| 100 | |||
| 101 | 28 | $this->username = $username; |
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| 102 | 28 | $this->password = $password; |
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| 103 | 28 | $this->options = $options; |
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| 104 | 28 | $this->pdoFactory = $pdoFactory ?? new PdoFactory(); |
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| 105 | 28 | } |
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| 106 | |||
| 107 | 18 | public function connect() |
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| 108 | { |
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| 109 | 18 | if ($this->isConnected()) { |
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| 110 | 15 | return; |
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| 111 | } |
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| 112 | |||
| 113 | 3 | $retries = $this->options['connectRetries'] ?? 0; |
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| 114 | do { |
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| 115 | try { |
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| 116 | 3 | $this->pdo = $this->pdoFactory->createPdo($this->dsn, $this->username, $this->password, $this->options); |
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| 117 | |||
| 118 | 2 | return; |
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| 119 | 2 | } catch (PDOException $e) { |
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| 120 | 2 | if ($this->isConnectionExceptionCausedByConnection($e) && $retries > 0) { |
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| 121 | // Sleep for 100 - 500 ms until next retry |
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| 122 | 2 | usleep(rand(100000, 500000)); |
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| 123 | } else { |
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| 124 | 1 | throw new ConnectionException($e); |
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| 125 | } |
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| 126 | } |
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| 127 | 2 | } while ($retries-- > 0); |
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| 128 | } |
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| 129 | |||
| 130 | /** |
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| 131 | * @param PDOException $exception |
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| 132 | * @return bool |
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| 133 | */ |
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| 134 | 2 | private function isConnectionExceptionCausedByConnection(PDOException $exception) |
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| 135 | { |
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| 136 | 2 | return in_array($exception->getCode(), [ |
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| 137 | 2 | 2002, // Can't connect to MySQL server (Socket) |
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| 138 | 2003, // Can't connect to MySQL server (TCP) |
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| 139 | 2006, // MySQL server has gone away |
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| 140 | 2013, // Lost connection to MySQL server during query |
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| 141 | ]); |
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| 142 | } |
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| 143 | |||
| 144 | /** |
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| 145 | * Close the database connection. |
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| 146 | */ |
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| 147 | 1 | public function disconnect() |
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| 148 | { |
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| 149 | 1 | $this->pdo = null; |
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| 150 | 1 | } |
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| 151 | |||
| 152 | /** |
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| 153 | */ |
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| 154 | 1 | public function reconnect() |
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| 155 | { |
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| 156 | 1 | $this->disconnect(); |
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| 157 | 1 | $this->connect(); |
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| 158 | 1 | } |
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| 159 | |||
| 160 | /** |
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| 161 | * Check if database connection is open. |
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| 162 | * |
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| 163 | * @return bool |
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| 164 | */ |
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| 165 | 19 | public function isConnected() |
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| 166 | { |
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| 167 | 19 | return ($this->pdo instanceof PDO); |
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| 168 | } |
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| 169 | |||
| 170 | /** |
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| 171 | * Returns the PDO handle. |
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| 172 | * |
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| 173 | * Can be used to gain access to any special PDO methods. |
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| 174 | * |
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| 175 | * @return PDO |
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| 176 | */ |
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| 177 | 4 | public function getPdo() |
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| 178 | { |
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| 179 | 4 | return $this->pdo; |
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| 180 | } |
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| 181 | |||
| 182 | /** |
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| 183 | * Creates and executes a PDO statement. |
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| 184 | * |
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| 185 | * @param string $sql |
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| 186 | * @param array $parameters |
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| 187 | * @return PDOStatement |
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| 188 | */ |
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| 189 | 7 | protected function executeQuery($sql, array $parameters = []) |
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| 190 | { |
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| 191 | 7 | $this->connect(); |
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| 192 | |||
| 193 | 7 | $dbParameters = $this->prepareParameters($parameters); |
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| 194 | try { |
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| 195 | 6 | $pdoStatement = $this->pdo->prepare($sql); |
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| 196 | 5 | $pdoStatement->execute($dbParameters); |
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| 197 | |||
| 198 | 5 | return $pdoStatement; |
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| 199 | 1 | } catch (PDOException $e) { |
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| 200 | 1 | throw new QueryException($e, $sql, $dbParameters); |
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| 201 | } |
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| 202 | } |
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| 203 | |||
| 204 | /** |
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| 205 | * Execute an SQL statement and return the number of affected rows. |
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| 206 | * |
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| 207 | * @param string $sql |
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| 208 | * @param array $parameters |
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| 209 | * @return int The number of rows affected |
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| 210 | */ |
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| 211 | 4 | public function exec($sql, array $parameters = []) |
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| 217 | |||
| 218 | /** |
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| 219 | * Execute an SQL statement and return the first row. |
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| 220 | * |
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| 221 | * @param string $sql |
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| 222 | * @param array $parameters |
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| 223 | * @param bool $indexedKeys |
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| 224 | * @return array|false |
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| 225 | */ |
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| 226 | 1 | public function fetchRow($sql, array $parameters = [], $indexedKeys = false) |
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| 232 | |||
| 233 | /** |
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| 234 | * Execute an SQL statement and return all rows as an array. |
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| 235 | * |
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| 236 | * @param string $sql |
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| 237 | * @param array $parameters |
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| 238 | * @param bool $indexedKeys |
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| 239 | * @return array |
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| 240 | */ |
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| 241 | 1 | public function fetchRows($sql, array $parameters = [], $indexedKeys = false) |
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| 247 | |||
| 248 | /** |
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| 249 | * Execute an SQL statement and return the first column of the first row. |
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| 250 | * |
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| 251 | * @param string $sql |
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| 252 | * @param array $parameters |
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| 253 | * @return string|false |
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| 254 | */ |
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| 255 | 1 | public function fetchValue($sql, array $parameters = []) |
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| 261 | |||
| 262 | /** |
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| 263 | * Quote a value for a safe use in query (eg. bla'bla -> 'bla''bla'). |
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| 264 | * |
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| 265 | * @param mixed $value |
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| 266 | * @return string |
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| 267 | */ |
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| 268 | 1 | public function quote($value) |
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| 274 | |||
| 275 | /** |
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| 276 | * Get id of the last inserted row. |
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| 277 | * |
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| 278 | * @return int |
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| 279 | */ |
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| 280 | 1 | public function getLastInsertId() |
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| 286 | |||
| 287 | /** |
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| 288 | * Prepare parameters for database use. |
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| 289 | * |
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| 290 | * @param array $parameters |
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| 291 | * @return array |
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| 292 | */ |
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| 293 | 7 | protected function prepareParameters(array $parameters = []) |
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| 310 | |||
| 311 | /** |
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| 312 | * Begin transaction (turns off autocommit mode). |
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| 313 | * |
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| 314 | * @param bool $onlyIfNoActiveTransaction |
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| 315 | * @return bool |
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| 316 | */ |
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| 317 | 4 | public function beginTransaction($onlyIfNoActiveTransaction = false) |
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| 330 | |||
| 331 | /** |
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| 332 | * Commits current active transaction (restores autocommit mode). |
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| 333 | */ |
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| 334 | 2 | public function commit() |
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| 341 | |||
| 342 | /** |
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| 343 | * Rolls back current active transaction (restores autocommit mode). |
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| 344 | */ |
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| 345 | 2 | public function rollBack() |
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| 352 | |||
| 353 | /** |
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| 354 | * @return bool |
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| 355 | */ |
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| 356 | 3 | public function hasActiveTransaction() |
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| 360 | |||
| 361 | /** |
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| 362 | * @param string $table |
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| 363 | * @param array $data |
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| 364 | * @param bool $updateOnDuplicateKey |
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| 365 | * @return int The number of rows affected |
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| 366 | */ |
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| 367 | 3 | public function insert($table, array $data, $updateOnDuplicateKey = false) |
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| 392 | |||
| 393 | /** |
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| 394 | * @param array $assignmentData |
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| 395 | * @return string |
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| 396 | */ |
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| 397 | 2 | protected function getAssignmentSql(array $assignmentData) |
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| 406 | |||
| 407 | /** |
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| 408 | * @param string $table |
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| 409 | * @param array $data |
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| 410 | * @param string $whereSql |
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| 411 | * @param array $whereParameters |
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| 412 | * @return int The number of rows affected |
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| 413 | */ |
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| 414 | 1 | public function update($table, array $data, $whereSql = '', array $whereParameters = []) |
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| 428 | } |
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| 429 |
If you suppress an error, we recommend checking for the error condition explicitly: