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 | * Constructor. |
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| 58 | * |
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| 59 | * @param string|PDO $hostDsnOrPdo A MySQL host, a dsn or an existing PDO instance. |
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| 60 | * @param string|null $username |
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| 61 | * @param string|null $password |
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| 62 | * @param string|null $database |
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| 63 | * @param array $options |
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| 64 | */ |
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| 65 | 23 | public function __construct( |
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| 66 | $hostDsnOrPdo, |
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| 67 | $username = null, |
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| 68 | $password = null, |
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| 69 | $database = null, |
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| 70 | array $options = [] |
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| 71 | ) { |
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| 72 | 23 | if ($hostDsnOrPdo instanceof PDO) { |
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| 73 | 23 | $this->pdo = $hostDsnOrPdo; |
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| 74 | } elseif (strpos($hostDsnOrPdo, ':') !== false) { |
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| 75 | $this->dsn = $hostDsnOrPdo; |
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| 76 | } else { |
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| 77 | $this->dsn = "mysql:host={$hostDsnOrPdo}" . ($database ? ";dbname={$database}" : ''); |
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| 78 | } |
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| 79 | |||
| 80 | 23 | $this->username = $username; |
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| 81 | 23 | $this->password = $password; |
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| 82 | 23 | $this->options = $options; |
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| 83 | 23 | } |
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| 84 | |||
| 85 | /** |
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| 86 | */ |
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| 87 | 15 | public function connect() |
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| 88 | { |
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| 89 | 15 | if ($this->isConnected()) { |
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| 90 | 15 | return; |
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| 91 | } |
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| 92 | |||
| 93 | $retries = isset($this->options['connectRetries'])? $this->options['connectRetries'] : 0; |
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| 94 | do { |
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| 95 | try { |
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| 96 | $defaultPdoOptions = [ |
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| 97 | PDO::ATTR_TIMEOUT => 5, |
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| 98 | // We want emulation by default (faster for single queries). Disable if you want to |
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| 99 | // use proper native prepared statements |
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| 100 | PDO::ATTR_EMULATE_PREPARES => true, |
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| 101 | PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, |
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| 102 | PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC, |
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| 103 | ]; |
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| 104 | $pdoOptions = $defaultPdoOptions + (isset($this->options['pdo']) ? $this->options['pdo'] : []); |
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| 105 | |||
| 106 | $this->pdo = new PDO( |
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| 107 | $this->dsn, |
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| 108 | $this->username, |
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| 109 | $this->password, |
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| 110 | $pdoOptions |
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| 111 | ); |
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| 112 | |||
| 113 | return; |
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| 114 | } catch (PDOException $e) { |
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| 115 | if ($this->isConnectionExceptionCausedByConnection($e) && $retries > 0) { |
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| 116 | // Sleep for 100 - 500 ms until next retry |
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| 117 | usleep(rand(100000, 500000)); |
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| 118 | } else { |
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| 119 | throw new ConnectionException($e); |
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| 120 | } |
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| 121 | } |
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| 122 | |||
| 123 | } while ($retries-- > 0); |
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| 124 | } |
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| 125 | |||
| 126 | /** |
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| 127 | * @param PDOException $exception |
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| 128 | * @return bool |
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| 129 | */ |
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| 130 | private function isConnectionExceptionCausedByConnection(PDOException $exception) |
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| 131 | { |
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| 132 | return in_array($exception->getCode(), [ |
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| 133 | 2002, // Can't connect to MySQL server (Socket) |
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| 134 | 2003, // Can't connect to MySQL server (TCP) |
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| 135 | 2006, // MySQL server has gone away |
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| 136 | 2013, // Lost connection to MySQL server during query |
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| 137 | ]); |
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| 138 | } |
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| 139 | |||
| 140 | /** |
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| 141 | * Close the database connection. |
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| 142 | */ |
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| 143 | 1 | public function disconnect() |
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| 147 | |||
| 148 | /** |
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| 149 | */ |
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| 150 | 1 | public function reconnect() |
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| 155 | |||
| 156 | /** |
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| 157 | * Check if database connection is open. |
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| 158 | * |
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| 159 | * @return bool |
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| 160 | */ |
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| 161 | 16 | public function isConnected() |
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| 165 | |||
| 166 | /** |
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| 167 | * Returns the PDO handle. |
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| 168 | * |
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| 169 | * Can be used to gain access to any special PDO methods. |
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| 170 | * |
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| 171 | * @return PDO |
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| 172 | */ |
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| 173 | 2 | public function getPdo() |
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| 177 | |||
| 178 | /** |
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| 179 | * Creates and executes a PDO statement. |
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| 180 | * |
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| 181 | * @param string $sql |
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| 182 | * @param array $parameters |
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| 183 | * @return PDOStatement |
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| 184 | */ |
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| 185 | 7 | protected function executeQuery($sql, array $parameters = []) |
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| 199 | |||
| 200 | /** |
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| 201 | * Execute an SQL statement and return the number of affected rows. |
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| 202 | * |
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| 203 | * @param string $sql |
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| 204 | * @param array $parameters |
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| 205 | * @return int The number of rows affected |
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| 206 | */ |
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| 207 | 4 | public function exec($sql, array $parameters = []) |
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| 213 | |||
| 214 | /** |
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| 215 | * Execute an SQL statement and return the first row. |
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| 216 | * |
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| 217 | * @param string $sql |
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| 218 | * @param array $parameters |
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| 219 | * @param bool $indexedKeys |
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| 220 | * @return array|false |
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| 221 | */ |
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| 222 | 1 | public function fetchRow($sql, array $parameters = [], $indexedKeys = false) |
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| 228 | |||
| 229 | /** |
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| 230 | * Execute an SQL statement and return all rows as an array. |
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| 231 | * |
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| 232 | * @param string $sql |
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| 233 | * @param array $parameters |
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| 234 | * @param bool $indexedKeys |
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| 235 | * @return array |
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| 236 | */ |
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| 237 | 1 | public function fetchRows($sql, array $parameters = [], $indexedKeys = false) |
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| 243 | |||
| 244 | /** |
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| 245 | * Execute an SQL statement and return the first column of the first row. |
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| 246 | * |
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| 247 | * @param string $sql |
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| 248 | * @param array $parameters |
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| 249 | * @return string|false |
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| 250 | */ |
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| 251 | 1 | public function fetchValue($sql, array $parameters = []) |
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| 257 | |||
| 258 | /** |
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| 259 | * Quote a value for a safe use in query (eg. bla'bla -> 'bla''bla'). |
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| 260 | * |
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| 261 | * @param mixed $value |
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| 262 | * @return string |
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| 263 | */ |
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| 264 | 1 | public function quote($value) |
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| 270 | |||
| 271 | /** |
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| 272 | * Get id of the last inserted row. |
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| 273 | * |
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| 274 | * @return int |
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| 275 | */ |
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| 276 | 1 | public function getLastInsertId() |
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| 282 | |||
| 283 | /** |
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| 284 | * Prepare parameters for database use. |
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| 285 | * |
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| 286 | * @param array $parameters |
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| 287 | * @return array |
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| 288 | */ |
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| 289 | 7 | protected function prepareParameters(array $parameters = []) |
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| 290 | { |
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| 291 | 7 | foreach ($parameters as &$parameterValue) { |
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| 292 | 6 | if (is_bool($parameterValue)) { |
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| 293 | 1 | $parameterValue = (int) $parameterValue; |
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| 294 | 6 | } elseif ($parameterValue instanceof \DateTimeInterface) { |
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| 295 | 1 | $parameterValue = $parameterValue->format('Y-m-d H:i:s'); |
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| 296 | 5 | } elseif (!is_scalar($parameterValue) && $parameterValue !== null) { |
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| 297 | 1 | throw new \InvalidArgumentException( |
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| 298 | 6 | sprintf('Invalid db parameter type "%s"', gettype($parameterValue)) |
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| 299 | ); |
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| 300 | } |
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| 301 | } |
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| 302 | 6 | unset($parameterValue); |
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| 303 | |||
| 304 | 6 | return $parameters; |
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| 305 | } |
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| 306 | |||
| 307 | /** |
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| 308 | * Begin transaction (turns off autocommit mode). |
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| 309 | * |
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| 310 | * @param bool $onlyIfNoActiveTransaction |
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| 311 | * @return bool |
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| 312 | */ |
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| 313 | 4 | public function beginTransaction($onlyIfNoActiveTransaction = false) |
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| 326 | |||
| 327 | /** |
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| 328 | * Commits current active transaction (restores autocommit mode). |
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| 329 | */ |
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| 330 | 2 | public function commit() |
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| 337 | |||
| 338 | /** |
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| 339 | * Rolls back current active transaction (restores autocommit mode). |
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| 340 | */ |
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| 341 | 2 | public function rollBack() |
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| 348 | |||
| 349 | /** |
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| 350 | * @return bool |
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| 351 | */ |
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| 352 | 3 | public function hasActiveTransaction() |
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| 356 | |||
| 357 | /** |
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| 358 | * @param string $table |
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| 359 | * @param array $data |
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| 360 | * @param bool $updateOnDuplicateKey |
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| 361 | * @return int The number of rows affected |
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| 362 | */ |
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| 363 | 3 | public function insert($table, array $data, $updateOnDuplicateKey = false) |
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| 388 | |||
| 389 | /** |
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| 390 | * @param array $assignmentData |
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| 391 | * @return string |
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| 392 | */ |
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| 393 | 2 | protected function getAssignmentSql(array $assignmentData) |
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| 402 | |||
| 403 | /** |
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| 404 | * @param string $table |
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| 405 | * @param array $data |
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| 406 | * @param string $whereSql |
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| 407 | * @param array $whereParameters |
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| 408 | * @return int The number of rows affected |
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| 409 | */ |
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| 410 | 1 | public function update($table, array $data, $whereSql = '', array $whereParameters = []) |
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| 424 | } |
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| 425 |