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 | 18 | public function __construct( |
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| 84 | |||
| 85 | /** |
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| 86 | */ |
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| 87 | 13 | public function connect() |
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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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| 139 | |||
| 140 | /** |
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| 141 | * Close 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 | * Check if database connection is open. |
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| 150 | * |
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| 151 | * @return bool |
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| 152 | */ |
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| 153 | 14 | public function isConnected() |
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| 157 | |||
| 158 | /** |
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| 159 | * Returns the PDO handle. |
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| 160 | * |
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| 161 | * Can be used to gain access to any special PDO methods. |
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| 162 | * |
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| 163 | * @return PDO |
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| 164 | */ |
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| 165 | 2 | public function getPdo() |
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| 169 | |||
| 170 | /** |
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| 171 | * Creates and executes a PDO statement. |
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| 172 | * |
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| 173 | * @param string $sql |
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| 174 | * @param array $parameters |
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| 175 | * @return PDOStatement |
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| 176 | */ |
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| 177 | 5 | protected function executeQuery($sql, array $parameters = []) |
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| 190 | |||
| 191 | /** |
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| 192 | * Execute an SQL statement and return the number of affected rows. |
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| 193 | * |
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| 194 | * @param string $sql |
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| 195 | * @param array $parameters |
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| 196 | * @return int The number of rows affected |
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| 197 | */ |
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| 198 | 2 | public function exec($sql, array $parameters = []) |
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| 204 | |||
| 205 | /** |
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| 206 | * Execute an SQL statement and return the first row. |
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| 207 | * |
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| 208 | * @param string $sql |
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| 209 | * @param array $parameters |
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| 210 | * @param bool $indexedKeys |
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| 211 | * @return array|false |
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| 212 | */ |
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| 213 | 1 | public function fetchRow($sql, array $parameters = [], $indexedKeys = false) |
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| 219 | |||
| 220 | /** |
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| 221 | * Execute an SQL statement and return all rows as an array. |
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| 222 | * |
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| 223 | * @param string $sql |
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| 224 | * @param array $parameters |
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| 225 | * @param bool $indexedKeys |
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| 226 | * @return array |
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| 227 | */ |
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| 228 | 1 | public function fetchAll($sql, array $parameters = [], $indexedKeys = false) |
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| 234 | |||
| 235 | /** |
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| 236 | * Execute an SQL statement and return the first column of the first row. |
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| 237 | * |
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| 238 | * @param string $sql |
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| 239 | * @param array $parameters |
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| 240 | * @return string|false |
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| 241 | */ |
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| 242 | 1 | public function fetchOne($sql, array $parameters = []) |
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| 248 | |||
| 249 | /** |
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| 250 | * Quote a value for a safe use in query (eg. bla'bla -> 'bla''bla'). |
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| 251 | * |
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| 252 | * @param mixed $value |
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| 253 | * @return string |
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| 254 | */ |
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| 255 | 1 | public function quote($value) |
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| 261 | |||
| 262 | /** |
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| 263 | * Get id of the last inserted row. |
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| 264 | * |
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| 265 | * @return int |
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| 266 | */ |
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| 267 | 1 | public function getLastInsertId() |
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| 273 | |||
| 274 | /** |
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| 275 | * Prepare parameters for database use. |
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| 276 | * |
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| 277 | * @param array $parameters |
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| 278 | * @return array |
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| 279 | */ |
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| 280 | 4 | protected function prepareParameters(array $parameters = []) |
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| 291 | |||
| 292 | /** |
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| 293 | * Begin transaction (turns off autocommit mode). |
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| 294 | * |
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| 295 | * @param bool $onlyIfNoActiveTransaction |
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| 296 | * @return bool |
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| 297 | */ |
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| 298 | 4 | public function beginTransaction($onlyIfNoActiveTransaction = false) |
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| 311 | |||
| 312 | /** |
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| 313 | * Commits current active transaction (restores autocommit mode). |
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| 314 | */ |
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| 315 | 2 | public function commit() |
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| 322 | |||
| 323 | /** |
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| 324 | * Rolls back current active transaction (restores autocommit mode). |
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| 325 | */ |
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| 326 | 2 | public function rollBack() |
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| 333 | |||
| 334 | /** |
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| 335 | * @return bool |
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| 336 | */ |
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| 337 | 3 | public function hasActiveTransaction() |
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| 341 | |||
| 342 | /** |
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| 343 | * @param string $table |
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| 344 | * @param array $data |
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| 345 | * @return int The number of rows affected |
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| 346 | */ |
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| 347 | 1 | public function insert($table, array $data) |
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| 359 | |||
| 360 | /** |
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| 361 | * @param string $table |
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| 362 | * @param array $data |
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| 363 | * @param string $whereSql |
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| 364 | * @param array $whereParameters |
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| 365 | * @return int The number of rows affected |
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| 366 | */ |
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| 367 | 1 | public function update($table, array $data, $whereSql = '', array $whereParameters = []) |
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| 383 | } |
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| 384 |