Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like SqlGenerator 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 SqlGenerator, and based on these observations, apply Extract Interface, too.
1 | <?php |
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36 | class SqlGenerator |
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37 | { |
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38 | use UtilContainerAwareTrait; |
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39 | |||
40 | |||
41 | /** |
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42 | * Db connection |
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43 | * |
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44 | * @var object |
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45 | */ |
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46 | protected $db; |
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47 | |||
48 | /** |
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49 | * Param array index by SQL part |
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50 | * |
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51 | * @var array |
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52 | */ |
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53 | protected $paramPart = []; |
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54 | |||
55 | /** |
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56 | * Generated SQL string part |
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57 | * |
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58 | * @var string |
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59 | */ |
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60 | protected $sqlPart = []; |
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61 | |||
62 | |||
63 | /** |
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64 | * Constructor |
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65 | * |
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66 | * @param Adodb &$db Db object |
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67 | */ |
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68 | public function __construct(&$db) |
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74 | |||
75 | |||
76 | /** |
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77 | * Clear all or some parts set param |
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78 | * |
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79 | * @param string $part |
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80 | */ |
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81 | public function clear($part = '') |
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114 | |||
115 | |||
116 | /** |
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117 | * Generate DELETE sql |
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118 | * |
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119 | * @param array $part |
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120 | * @return string |
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121 | */ |
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122 | public function genDelete($part = null) |
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141 | |||
142 | |||
143 | /** |
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144 | * Generate INSERT sql |
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145 | * |
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146 | * @param array $part |
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147 | * @return string |
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148 | */ |
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149 | public function genInsert($part = []) |
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168 | |||
169 | |||
170 | /** |
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171 | * Generate SELECT sql |
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172 | * |
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173 | * @param array $part |
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174 | * @return string |
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175 | */ |
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176 | View Code Duplication | public function genSelect($part = []) |
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198 | |||
199 | |||
200 | /** |
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201 | * Generate SQL part, convert param array to string with separator |
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202 | * |
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203 | * @param mixed $param |
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204 | * @param string $separator Should have space included |
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205 | * @return string |
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206 | */ |
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207 | View Code Duplication | protected function genSqlArray($param, $separator = ', ') |
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223 | |||
224 | |||
225 | /** |
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226 | * Generate SQL part, which param is array and need use AS in it |
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227 | * |
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228 | * @param mixed $param Param content, array or string, |
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229 | * {k: v} means 'k AS v', |
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230 | * [v] means 'v AS v', |
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231 | * remember to check $reverse param below. |
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232 | * @param boolean $useAs Sybase table alias can't use AS |
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233 | * @param boolean $quote AS column alias, need to be quoted(true), |
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234 | * AS table alias, need not to be quoted(false). |
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235 | * @param boolean $reverse Default true: {k: v} means 'v AS k'. |
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236 | * Because array key must be unique, and a |
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237 | * table can have many alias, so use unique |
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238 | * alias as key in param array. Also this |
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239 | * will make define code pretty and short, |
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240 | * especially when mixed items with/without |
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241 | * alias. Eg: {tbl1, a: tbl2} |
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242 | * @return string |
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243 | */ |
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244 | View Code Duplication | protected function genSqlArrayAs( |
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282 | |||
283 | |||
284 | /** |
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285 | * Generate SQL part, SET sub-parse of UPDATE |
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286 | * |
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287 | * @param array $param Array only, string will use original value. |
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288 | * Array($k=>$v) means 'SET $k = $v, ' in sql, |
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289 | * @return string |
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290 | */ |
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291 | View Code Duplication | protected function genSqlArraySet($param) |
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309 | |||
310 | |||
311 | /** |
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312 | * Generate SQL part, VALUES sub-parse of INSERT |
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313 | * |
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314 | * @param array $param Array only, string will use original value. |
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315 | * Array($k=>$v) means '($k) VALUES ($v)' in sql. |
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316 | * @return string |
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317 | */ |
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318 | View Code Duplication | protected function genSqlArrayValues($param) |
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338 | |||
339 | |||
340 | /** |
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341 | * Smart quote value in sql, by check columns type |
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342 | * |
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343 | * @param string $tbl |
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344 | * @param string $col |
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345 | * @param mixed $val |
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346 | * @return string |
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347 | */ |
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348 | protected function genSqlQuote($tbl, $col, $val) |
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352 | |||
353 | |||
354 | /** |
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355 | * Generate UPDATE sql |
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356 | * @param array $part |
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357 | * @return string |
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358 | */ |
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359 | View Code Duplication | public function genUpdate($part = []) |
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378 | |||
379 | |||
380 | /** |
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381 | * Get result SQL statement |
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382 | * |
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383 | * Notice: If $config include SELECT, UPDATE, INSERT, DELETE |
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384 | * simultaneously, system will select the first occurs by raw order. |
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385 | * |
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386 | * @param array $config {SELECT: , FROM: ...} |
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387 | * If omit, use $this->paramPart |
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388 | * @param string $part SELECT/UPDATE ... etc |
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389 | * @return string |
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390 | */ |
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391 | public function get($config = [], $part = '') |
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421 | |||
422 | |||
423 | /** |
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424 | * Get DELETE sql only |
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425 | * |
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426 | * @param array $config |
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427 | * @return string |
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428 | */ |
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429 | public function getDelete($config = []) |
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433 | |||
434 | |||
435 | /** |
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436 | * Get INSERT sql only |
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437 | * |
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438 | * @param array $config |
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439 | * @return string |
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440 | */ |
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441 | public function getInsert($config = []) |
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445 | |||
446 | |||
447 | /** |
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448 | * Get SQL statement for PREPARE usage |
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449 | * |
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450 | * Used need replace actual value with Adodb::param(col), to generate sql |
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451 | * use placeholder (? or :name by db type), this method will auto remove |
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452 | * quote. |
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453 | * |
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454 | * When execute a prepared SQL, db system will auto add quote, but it |
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455 | * depends on type of value, NOT type of db column. |
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456 | * |
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457 | * Known replaceQuote list: |
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458 | * mssql: double single-quote |
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459 | * mysql: backslash-quote |
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460 | * |
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461 | * @param array $param |
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462 | * @return string |
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463 | */ |
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464 | View Code Duplication | public function getPrepared($param = []) |
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486 | |||
487 | |||
488 | /** |
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489 | * Get SELECT sql only |
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490 | * |
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491 | * @param array $config |
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492 | * @return string |
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493 | */ |
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494 | public function getSelect($config = []) |
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498 | |||
499 | |||
500 | /** |
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501 | * Get UPDATE sql only |
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502 | * |
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503 | * @param array $config |
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504 | * @return string |
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505 | */ |
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506 | public function getUpdate($config = []) |
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510 | |||
511 | |||
512 | /** |
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513 | * Set param |
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514 | * |
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515 | * Un-recognized clause is ignored. |
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516 | * |
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517 | * @param array &$config |
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518 | * @return string |
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519 | */ |
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520 | public function set(&$config) |
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550 | |||
551 | |||
552 | /** |
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553 | * Set and treat DELETE param |
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554 | * |
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555 | * @param mixed $param |
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556 | * @return string |
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557 | */ |
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558 | View Code Duplication | public function setDelete($param) |
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566 | |||
567 | |||
568 | /** |
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569 | * Set and treat FROM param |
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570 | * |
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571 | * @param mixed $param |
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572 | * @return string |
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573 | */ |
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574 | View Code Duplication | public function setFrom($param) |
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585 | |||
586 | |||
587 | /** |
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588 | * Set and treat GROUP BY param |
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589 | * |
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590 | * @param mixed $param |
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591 | * @return string |
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592 | */ |
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593 | View Code Duplication | public function setGroupby($param) |
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601 | |||
602 | |||
603 | /** |
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604 | * Set and treat HAVING param |
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605 | * |
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606 | * @param mixed $param |
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607 | * @return string |
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608 | */ |
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609 | View Code Duplication | public function setHaving($param) |
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619 | |||
620 | |||
621 | /** |
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622 | * Set and treat INSERT param |
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623 | * |
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624 | * @param mixed $param |
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625 | * @return string |
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626 | */ |
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627 | View Code Duplication | public function setInsert($param) |
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638 | |||
639 | |||
640 | /** |
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641 | * Set and treat LIMIT param |
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642 | * |
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643 | * @param mixed $param |
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644 | * @return string |
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645 | */ |
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646 | public function setLimit($param) |
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662 | |||
663 | |||
664 | /** |
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665 | * Set and treat ORDER BY param |
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666 | * |
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667 | * @param mixed $param |
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668 | * @return string |
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669 | */ |
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670 | View Code Duplication | public function setOrderby($param) |
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678 | |||
679 | |||
680 | /** |
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681 | * Set and treat SELECT param |
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682 | * |
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683 | * @param mixed $param |
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684 | * @return string |
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685 | */ |
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686 | View Code Duplication | public function setSelect($param) |
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694 | |||
695 | |||
696 | /** |
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697 | * Set and treat SET param |
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698 | * |
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699 | * @param mixed $param |
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700 | * @return string |
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701 | */ |
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702 | View Code Duplication | public function setSet($param) |
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712 | |||
713 | |||
714 | /** |
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715 | * Set and treat UPDATE param |
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716 | * |
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717 | * @param mixed $param |
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718 | * @return string |
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719 | */ |
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720 | View Code Duplication | public function setUpdate($param) |
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731 | |||
732 | |||
733 | /** |
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734 | * Set and treat VALUES param |
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735 | * |
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736 | * @param mixed $param |
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737 | * @return string |
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738 | */ |
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739 | public function setValues($param) |
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749 | |||
750 | |||
751 | /** |
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752 | * Set and treat WHERE param |
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753 | * |
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754 | * @param mixed $param |
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755 | * @return string |
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756 | */ |
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757 | View Code Duplication | public function setWhere($param) |
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767 | } |
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768 |
This check looks for variable assignements that are either overwritten by other assignments or where the variable is not used subsequently.
Both the
$myVar
assignment in line 1 and the$higher
assignment in line 2 are dead. The first because$myVar
is never used and the second because$higher
is always overwritten for every possible time line.