Complex classes like Database 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 Database, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 6 | Class Database { |
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| 7 | |||
| 8 | /** |
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| 9 | * Constant to indicate whether the query is a write operation. |
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| 10 | * |
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| 11 | * @var integer |
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| 12 | */ |
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| 13 | const __WRITE_OPERATION__ = 0; |
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| 14 | |||
| 15 | /** |
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| 16 | * Constant to indicate whether the query is a write operation |
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| 17 | * |
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| 18 | * @var integer |
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| 19 | */ |
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| 20 | const __READ_OPERATION__ = 1; |
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| 21 | |||
| 22 | /** |
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| 23 | * An instance of the current PDO object |
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| 24 | * @var PDO |
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| 25 | */ |
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| 26 | public $conn = null; |
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| 27 | |||
| 28 | /** |
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| 29 | * Sets the current `$_log` to be an empty array |
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| 30 | * |
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| 31 | * @var array |
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| 32 | */ |
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| 33 | public $log = array(); |
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| 34 | |||
| 35 | /** |
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| 36 | * The number of queries this class has executed, defaults to 0. |
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| 37 | * |
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| 38 | * @var integer |
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| 39 | */ |
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| 40 | protected $_query_count = 0; |
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| 41 | |||
| 42 | /** |
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| 43 | * The table prefix for this connection. Queries to be written using |
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| 44 | * a `tbl_table_name` syntax, where `tbl_` will be replaced by this |
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| 45 | * variable. By default it is `sym_` but it configured in the configuration |
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| 46 | * |
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| 47 | * @var string |
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| 48 | */ |
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| 49 | protected $_prefix = 'sym_'; |
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| 50 | |||
| 51 | /** |
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| 52 | * Whether query caching is enabled or not. By default this set |
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| 53 | * to true which will use SQL_CACHE to cache the results of queries |
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| 54 | * |
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| 55 | * @var boolean |
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| 56 | */ |
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| 57 | protected $_cache = true; |
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| 58 | |||
| 59 | /** |
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| 60 | * Whether to log this query in the internal `$log`. |
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| 61 | * Defaults to true |
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| 62 | * |
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| 63 | * @var boolean |
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| 64 | */ |
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| 65 | protected $_logging = true; |
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| 66 | |||
| 67 | /** |
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| 68 | * @var PDOStatement |
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| 69 | */ |
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| 70 | protected $_result = null; |
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| 71 | |||
| 72 | /** |
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| 73 | * @var array |
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| 74 | */ |
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| 75 | protected $_lastResult = array(); |
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| 76 | |||
| 77 | /** |
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| 78 | * @var string |
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| 79 | */ |
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| 80 | protected $_lastQuery = null; |
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| 81 | |||
| 82 | /** |
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| 83 | * @var string |
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| 84 | */ |
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| 85 | protected $_lastQueryHash = null; |
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| 86 | |||
| 87 | /** |
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| 88 | * Creates a new Database object given an associative array of configuration |
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| 89 | * parameters in `$config`. If `$config` contains a key, `pdo` then this |
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| 90 | * `Database` instance will use that PDO connection. Otherwise, `$config` |
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| 91 | * should include `driver`, `host`, `port`, `user`, `password` and an optional |
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| 92 | * array of PDO options in `options`. |
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| 93 | * |
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| 94 | * @param array $config |
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| 95 | */ |
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| 96 | public function __construct(array $config = array()) |
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| 111 | |||
| 112 | /** |
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| 113 | * Magic function that will flush the MySQL log and close the MySQL |
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| 114 | * connection when the MySQL class is removed or destroyed. |
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| 115 | * |
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| 116 | * @link http://php.net/manual/en/language.oop5.decon.php |
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| 117 | */ |
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| 118 | public function __destruct() |
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| 123 | |||
| 124 | /** |
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| 125 | * Resets the `result`, `lastResult`, `lastQuery` and lastQueryHash properties to `null`. |
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| 126 | * Called on each query and when the class is destroyed. |
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| 127 | */ |
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| 128 | public function flush() |
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| 135 | |||
| 136 | /** |
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| 137 | * Creates a PDO connection to the desired database given the parameters. |
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| 138 | * This will also set the error mode to be exceptions (handled by this class) |
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| 139 | * |
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| 140 | * @link http://www.php.net/manual/en/pdo.drivers.php |
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| 141 | * @param string $dsn |
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| 142 | * @param string $username |
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| 143 | * @param string $password |
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| 144 | * @param array $options |
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| 145 | * @return boolean |
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| 146 | */ |
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| 147 | public function connect($dsn = null, $username = null, $password = null, array $options = array()) |
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| 161 | |||
| 162 | /** |
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| 163 | * Returns the number of queries that has been executed |
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| 164 | * |
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| 165 | * @return integer |
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| 166 | */ |
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| 167 | public function queryCount() |
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| 171 | |||
| 172 | /** |
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| 173 | * Sets query caching to true, this will prepend all READ_OPERATION |
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| 174 | * queries with SQL_CACHE. Symphony be default enables caching. It |
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| 175 | * can be turned off by setting the query_cache parameter to 'off' in the |
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| 176 | * Symphony config file. |
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| 177 | * |
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| 178 | * @link http://dev.mysql.com/doc/refman/5.1/en/query-cache.html |
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| 179 | */ |
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| 180 | public function enableCaching() |
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| 184 | |||
| 185 | /** |
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| 186 | * Sets query caching to false, this will prepend all READ_OPERATION |
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| 187 | * queries will SQL_NO_CACHE. |
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| 188 | */ |
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| 189 | public function disableCaching() |
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| 193 | |||
| 194 | /** |
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| 195 | * Returns boolean if query caching is enabled or not |
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| 196 | * |
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| 197 | * @return boolean |
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| 198 | */ |
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| 199 | public function isCachingEnabled() |
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| 203 | |||
| 204 | /** |
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| 205 | * Enables the logging of queries |
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| 206 | */ |
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| 207 | public function enableLogging() |
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| 211 | |||
| 212 | /** |
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| 213 | * Sets logging to false |
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| 214 | */ |
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| 215 | public function disableLogging() |
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| 219 | |||
| 220 | /** |
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| 221 | * Returns boolean if logging is enabled or not |
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| 222 | * |
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| 223 | * @return boolean |
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| 224 | */ |
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| 225 | public function isLoggingEnabled() |
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| 229 | |||
| 230 | /** |
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| 231 | * Symphony uses a prefix for all it's database tables so it can live peacefully |
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| 232 | * on the same database as other applications. By default this is sym_, but it |
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| 233 | * can be changed when Symphony is installed. |
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| 234 | * |
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| 235 | * @param string $prefix |
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| 236 | * The table prefix for Symphony, by default this is sym_ |
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| 237 | */ |
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| 238 | public function setPrefix($prefix) |
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| 242 | |||
| 243 | /** |
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| 244 | * Returns the prefix used by Symphony for this Database instance. |
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| 245 | * |
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| 246 | * @since Symphony 2.4 |
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| 247 | * @return string |
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| 248 | */ |
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| 249 | public function getPrefix() |
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| 253 | |||
| 254 | /** |
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| 255 | * Given a string, replace the default table prefixes with the |
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| 256 | * table prefix for this database instance. |
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| 257 | * |
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| 258 | * @param string $query |
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| 259 | * @return string |
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| 260 | */ |
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| 261 | public function replaceTablePrefix($query) |
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| 269 | |||
| 270 | /** |
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| 271 | * Function looks over a query to determine if it's a READ or WRITE operation. |
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| 272 | * WRITE operations are any query that starts with: SET, CREATE, INSERT, REPLACE |
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| 273 | * ALTER, DELETE, UPDATE, OPTIMIZE, TRUNCATE or DROP. All other queries are considered |
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| 274 | * READ operations |
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| 275 | * |
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| 276 | * @param string $query |
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| 277 | * @return integer |
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| 278 | */ |
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| 279 | public function determineQueryType($query) |
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| 285 | |||
| 286 | /** |
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| 287 | * @param array $values |
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| 288 | * @return string |
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| 289 | */ |
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| 290 | public static function addPlaceholders(array $values = array()) |
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| 299 | |||
| 300 | /** |
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| 301 | * Given a query that has been prepared and an array of values to subsitute |
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| 302 | * into the query, the function will return the result. |
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| 303 | * |
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| 304 | * @param string $query |
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| 305 | * @param array $values |
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| 306 | * @return PDOStatement |
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| 307 | */ |
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| 308 | public function insert($query, array $values) |
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| 314 | |||
| 315 | /** |
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| 316 | * Returns the last insert ID from the previous query. This is |
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| 317 | * the value from an auto_increment field. |
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| 318 | * |
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| 319 | * @return integer |
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| 320 | * The last interested row's ID |
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| 321 | */ |
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| 322 | public function getInsertID() |
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| 326 | |||
| 327 | /** |
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| 328 | * Given a query that has been prepared and an array of values to subsitute |
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| 329 | * into the query, the function will return the result. |
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| 330 | * |
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| 331 | * @param string $query |
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| 332 | * @param array $values |
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| 333 | * @return PDOStatement |
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| 334 | */ |
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| 335 | public function update($query, array $values) |
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| 341 | |||
| 342 | /** |
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| 343 | * Given a query that has been prepared and an array of values to subsitute |
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| 344 | * into the query, the function will return the result. |
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| 345 | * |
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| 346 | * @param string $query |
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| 347 | * @param array $values |
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| 348 | * @return PDOStatement |
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| 349 | */ |
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| 350 | public function delete($query, array $values) |
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| 356 | |||
| 357 | /** |
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| 358 | * Given a query that has been prepared and an array of optional |
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| 359 | * parameters, this function will return the results of a query |
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| 360 | * as an array. |
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| 361 | * |
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| 362 | * @param string $query |
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| 363 | * @param array $params |
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| 364 | * - `fetch-type` = 'ASSOC'/'OBJECT' |
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| 365 | * Return result as array or an object |
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| 366 | * - `index` = 'column_name' |
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| 367 | * The name of a column in the table to use it's value to index |
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| 368 | * the result by. If this is omitted (and it is by default), an |
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| 369 | * array of associative arrays is returned, with the key being the |
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| 370 | * column names |
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| 371 | * `offset` = `0` |
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| 372 | * An integer representing the row to return |
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| 373 | * @param array $values |
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| 374 | * @return array |
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| 375 | */ |
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| 376 | public function fetch($query = null, array $params = array(), array $values = array()) |
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| 401 | |||
| 402 | /** |
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| 403 | * Takes an SQL string and creates a prepared statement. |
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| 404 | * |
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| 405 | * @link http://php.net/manual/en/pdo.prepare.php |
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| 406 | * @param string $query |
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| 407 | * @param array $driver_options |
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| 408 | * This array holds one or more key=>value pairs to set attribute values |
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| 409 | * for the DatabaseStatement object that this method returns. |
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| 410 | * @return DatabaseStatement |
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| 411 | */ |
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| 412 | public function prepare($query, array $driver_options = array()) |
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| 418 | |||
| 419 | /** |
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| 420 | * Create a transaction. |
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| 421 | * |
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| 422 | * @return DatabaseTransaction |
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| 423 | */ |
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| 424 | public function transaction() |
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| 428 | |||
| 429 | /** |
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| 430 | * Given a query that has been prepared and an array of values to subsitute |
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| 431 | * into the query, the function will return the result. Unlike `insert` and |
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| 432 | * `update`, this function is a bit of a catch all and will be able to populate |
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| 433 | * `$this->_lastResult` with an array of data. This function is usually used |
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| 434 | * via `fetch()`. |
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| 435 | * |
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| 436 | * @see fetch() |
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| 437 | * @param string $query |
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| 438 | * @param array $params |
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| 439 | * Supports `fetch-type` and `offset` parameters for the moment |
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| 440 | * @param array $values |
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| 441 | * If the `$query` has placeholders, this parameter will include the data |
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| 442 | * to subsitute into the placeholders |
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| 443 | * @return boolean |
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| 444 | */ |
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| 445 | public function query($query, array $params = array(), array $values = array()) |
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| 484 | |||
| 485 | /** |
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| 486 | * This function is actually responsible for subsituting the values into |
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| 487 | * the query and logging the query for basic profiling/debugging. |
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| 488 | * |
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| 489 | * @param string $query |
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| 490 | * @param array $values |
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| 491 | * @param boolean $close |
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| 492 | * If true, once the query is executed, the cursor will be closed, |
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| 493 | * otherwise it'll be left open for further manipulation (as done by |
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| 494 | * `query()`). Defaults to `true` |
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| 495 | * @return PDOStatement |
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| 496 | */ |
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| 497 | private function q($query, $values, $close = true) |
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| 542 | |||
| 543 | /** |
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| 544 | * Given an Exception, or called when an error occurs, this function will |
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| 545 | * fire the `QueryExecutionError` delegate and then raise a `DatabaseException` |
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| 546 | * |
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| 547 | * @uses QueryExecutionError |
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| 548 | * @throws DatabaseException |
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| 549 | * @param Exception $ex |
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| 550 | * The exception thrown while doing something with the Database |
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| 551 | * @return void |
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| 552 | */ |
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| 553 | public function error(Exception $ex = null) |
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| 601 | |||
| 602 | /** |
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| 603 | * Throw a new DatabaseException when given an original exception and a query. |
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| 604 | * |
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| 605 | * @param Exception $error |
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| 606 | * @param string $query |
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| 607 | * @param string $query_hash |
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| 608 | */ |
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| 609 | public function throwError(Exception $error, $query, $query_hash) |
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| 616 | |||
| 617 | /** |
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| 618 | * Function is called everytime a query is executed to log it for |
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| 619 | * basic profiling/debugging purposes |
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| 620 | * |
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| 621 | * @uses PostQueryExecution |
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| 622 | * @param string $query |
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| 623 | * @param string $query_hash |
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| 624 | * @param integer $stop |
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| 625 | */ |
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| 626 | public function logQuery($query, $query_hash, $stop) |
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| 675 | |||
| 676 | /** |
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| 677 | * Returns all the log entries by type. There are two valid types, |
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| 678 | * error and debug. If no type is given, the entire log is returned, |
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| 679 | * otherwise only log messages for that type are returned |
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| 680 | * |
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| 681 | * @param string $type |
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| 682 | * @return array |
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| 683 | * An array of associative array's. Log entries of the error type |
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| 684 | * return the query the error occurred on and the error number and |
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| 685 | * message from MySQL. Log entries of the debug type return the |
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| 686 | * the query and the start/stop time to indicate how long it took |
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| 687 | * to run |
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| 688 | */ |
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| 689 | public function debug($type = null) |
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| 695 | |||
| 696 | /** |
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| 697 | * Returns some basic statistics from the MySQL class about the |
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| 698 | * number of queries, the time it took to query and any slow queries. |
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| 699 | * A slow query is defined as one that took longer than 0.0999 seconds |
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| 700 | * This function is used by the Profile devkit |
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| 701 | * |
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| 702 | * @return array |
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| 703 | * An associative array with the number of queries, an array of slow |
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| 704 | * queries and the total query time. |
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| 705 | */ |
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| 706 | public function getStatistics() |
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| 722 | } |
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| 723 |
Our type inference engine has found an assignment to a property that is incompatible with the declared type of that property.
Either this assignment is in error or the assigned type should be added to the documentation/type hint for that property..