Complex classes like MySQL 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 MySQL, and based on these observations, apply Extract Interface, too.
1 | <?php |
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18 | class MySQL implements Database { |
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19 | /** @var array */ |
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20 | private static $tableFields = array(); |
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21 | /** @var PDO */ |
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22 | private $pdo; |
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23 | /** @var bool */ |
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24 | private $outerTransaction = false; |
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25 | /** @var AliasRegistry */ |
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26 | private $aliasRegistry; |
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27 | /** @var int */ |
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28 | private $transactionLevel = 0; |
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29 | /** @var QueryLoggers */ |
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30 | private $queryLoggers = 0; |
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31 | /** @var MySQLExceptionInterpreter */ |
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32 | private $exceptionInterpreter = 0; |
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33 | |||
34 | /** |
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35 | * @param PDO $pdo |
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36 | */ |
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37 | public function __construct(PDO $pdo) { |
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38 | if($pdo->getAttribute(PDO::ATTR_ERRMODE) === PDO::ERRMODE_SILENT) { |
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39 | $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); |
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40 | } |
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41 | $this->pdo = $pdo; |
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42 | $this->aliasRegistry = new AliasRegistry(); |
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43 | $this->queryLoggers = new QueryLoggers(); |
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44 | $this->exceptionInterpreter = new MySQLExceptionInterpreter(); |
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45 | } |
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46 | |||
47 | /** |
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48 | * @return QueryLoggers |
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49 | */ |
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50 | public function getQueryLoggers() { |
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53 | |||
54 | /** |
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55 | * @return AliasRegistry |
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56 | */ |
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57 | public function getAliasRegistry() { |
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60 | |||
61 | /** |
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62 | * @param string $query |
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63 | * @throws Exception |
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64 | * @return QueryStatement |
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65 | */ |
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66 | public function query($query) { |
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72 | |||
73 | /** |
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74 | * @param string $query |
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75 | * @throws Exception |
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76 | * @return QueryStatement |
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77 | */ |
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78 | public function prepare($query) { |
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84 | |||
85 | /** |
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86 | * @param string $query |
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87 | * @param array $params |
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88 | * @return int |
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89 | */ |
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90 | public function exec($query, array $params = array()) { |
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101 | |||
102 | /** |
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103 | * @return string |
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104 | */ |
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105 | public function getLastInsertId() { |
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108 | |||
109 | /** |
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110 | * @param string $table |
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111 | * @return array |
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112 | */ |
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113 | public function getTableFields($table) { |
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124 | |||
125 | /** |
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126 | * @param mixed $expression |
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127 | * @param array $arguments |
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128 | * @return string |
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129 | */ |
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130 | public function quoteExpression($expression, array $arguments = array()) { |
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146 | |||
147 | /** |
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148 | * @param mixed $value |
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149 | * @return string |
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150 | */ |
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151 | public function quote($value) { |
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165 | |||
166 | /** |
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167 | * @param string $field |
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168 | * @return string |
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169 | */ |
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170 | public function quoteField($field) { |
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180 | |||
181 | /** |
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182 | * @param array $fields |
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183 | * @return RunnableSelect |
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184 | */ |
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185 | public function select(array $fields = null) { |
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192 | |||
193 | /** |
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194 | * @param array $fields |
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195 | * @return Builder\RunnableInsert |
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196 | */ |
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197 | public function insert(array $fields = null) { |
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204 | |||
205 | /** |
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206 | * @param array $fields |
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207 | * @return Builder\RunnableUpdate |
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208 | */ |
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209 | public function update(array $fields = null) { |
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216 | |||
217 | /** |
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218 | * @return Builder\RunnableDelete |
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219 | */ |
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220 | public function delete() { |
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223 | |||
224 | /** |
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225 | * @return $this |
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226 | */ |
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227 | public function transactionStart() { |
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238 | |||
239 | /** |
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240 | * @return $this |
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241 | * @throws \Exception |
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242 | */ |
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243 | public function transactionCommit() { |
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248 | |||
249 | /** |
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250 | * @return $this |
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251 | * @throws \Exception |
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252 | */ |
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253 | public function transactionRollback() { |
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258 | |||
259 | /** |
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260 | * @param callable|null $callback |
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261 | * @return mixed |
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262 | * @throws \Exception |
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263 | * @throws null |
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264 | */ |
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265 | public function dryRun($callback = null) { |
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294 | |||
295 | /** |
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296 | * @param int|callable $tries |
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297 | * @param callable|null $callback |
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298 | * @return mixed |
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299 | * @throws \Exception |
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300 | * @throws null |
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301 | */ |
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302 | public function transaction($tries = 1, $callback = null) { |
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334 | |||
335 | /** |
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336 | * @param callable $fn |
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337 | * @return $this |
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338 | * @throws \Exception |
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339 | */ |
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340 | private function transactionEnd($fn) { |
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354 | |||
355 | /** |
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356 | * @param string $query |
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357 | * @param callable $fn |
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358 | * @return QueryStatement |
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359 | * @throws Exception |
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360 | */ |
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361 | private function buildQueryStatement($query, $fn) { |
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369 | |||
370 | /** |
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371 | * @param callable $fn |
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372 | * @return mixed |
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373 | */ |
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374 | private function exceptionHandler($fn) { |
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381 | |||
382 | /** |
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383 | * @return string |
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384 | */ |
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385 | private function genUniqueId() { |
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398 | } |
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399 |