Complex classes like Select 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 Select, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 21 | class Select extends AbstractQuery implements SelectInterface, SubselectInterface |
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| 22 | { |
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| 23 | use WhereTrait; |
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| 24 | use LimitOffsetTrait { limit as setLimit; offset as setOffset; } |
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| 25 | |||
| 26 | /** |
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| 27 | * |
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| 28 | * An array of union SELECT statements. |
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| 29 | * |
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| 30 | * @var array |
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| 31 | * |
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| 32 | */ |
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| 33 | protected $union = array(); |
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| 34 | |||
| 35 | /** |
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| 36 | * |
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| 37 | * Is this a SELECT FOR UPDATE? |
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| 38 | * |
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| 39 | * @var |
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| 40 | * |
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| 41 | */ |
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| 42 | protected $for_update = false; |
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| 43 | |||
| 44 | /** |
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| 45 | * |
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| 46 | * The columns to be selected. |
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| 47 | * |
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| 48 | * @var array |
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| 49 | * |
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| 50 | */ |
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| 51 | protected $cols = array(); |
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| 52 | |||
| 53 | /** |
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| 54 | * |
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| 55 | * Select from these tables; includes JOIN clauses. |
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| 56 | * |
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| 57 | * @var array |
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| 58 | * |
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| 59 | */ |
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| 60 | protected $from = array(); |
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| 61 | |||
| 62 | /** |
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| 63 | * |
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| 64 | * The current key in the `$from` array. |
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| 65 | * |
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| 66 | * @var int |
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| 67 | * |
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| 68 | */ |
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| 69 | protected $from_key = -1; |
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| 70 | |||
| 71 | /** |
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| 72 | * |
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| 73 | * Tracks which JOIN clauses are attached to which FROM tables. |
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| 74 | * |
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| 75 | * @var array |
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| 76 | * |
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| 77 | */ |
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| 78 | protected $join = array(); |
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| 79 | |||
| 80 | /** |
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| 81 | * |
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| 82 | * GROUP BY these columns. |
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| 83 | * |
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| 84 | * @var array |
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| 85 | * |
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| 86 | */ |
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| 87 | protected $group_by = array(); |
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| 88 | |||
| 89 | /** |
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| 90 | * |
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| 91 | * The list of HAVING conditions. |
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| 92 | * |
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| 93 | * @var array |
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| 94 | * |
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| 95 | */ |
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| 96 | protected $having = array(); |
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| 97 | |||
| 98 | /** |
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| 99 | * |
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| 100 | * The page number to select. |
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| 101 | * |
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| 102 | * @var int |
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| 103 | * |
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| 104 | */ |
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| 105 | protected $page = 0; |
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| 106 | |||
| 107 | /** |
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| 108 | * |
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| 109 | * The number of rows per page. |
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| 110 | * |
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| 111 | * @var int |
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| 112 | * |
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| 113 | */ |
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| 114 | protected $paging = 10; |
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| 115 | |||
| 116 | /** |
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| 117 | * |
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| 118 | * Tracks table references to avoid duplicate identifiers. |
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| 119 | * |
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| 120 | * @var array |
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| 121 | * |
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| 122 | */ |
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| 123 | protected $table_refs = array(); |
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| 124 | |||
| 125 | /** |
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| 126 | * |
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| 127 | * Returns this query object as an SQL statement string. |
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| 128 | * |
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| 129 | * @return string An SQL statement string. |
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| 130 | * |
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| 131 | */ |
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| 132 | 189 | public function getStatement() |
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| 133 | { |
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| 134 | 189 | $union = ''; |
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| 135 | 189 | if (! empty($this->union)) { |
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| 136 | 15 | $union = implode(PHP_EOL, $this->union) . PHP_EOL; |
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| 137 | 15 | } |
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| 138 | 189 | return $union . $this->build(); |
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| 139 | } |
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| 140 | |||
| 141 | /** |
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| 142 | * |
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| 143 | * Sets the number of rows per page. |
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| 144 | * |
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| 145 | * @param int $paging The number of rows to page at. |
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| 146 | * |
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| 147 | * @return $this |
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| 148 | * |
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| 149 | */ |
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| 150 | 10 | public function setPaging($paging) |
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| 151 | { |
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| 152 | 10 | $this->paging = (int) $paging; |
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| 153 | 10 | if ($this->page) { |
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| 154 | 5 | $this->setPagingLimitOffset(); |
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| 155 | 5 | } |
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| 156 | 10 | return $this; |
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| 157 | } |
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| 158 | |||
| 159 | /** |
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| 160 | * |
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| 161 | * Gets the number of rows per page. |
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| 162 | * |
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| 163 | * @return int The number of rows per page. |
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| 164 | * |
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| 165 | */ |
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| 166 | 10 | public function getPaging() |
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| 170 | |||
| 171 | /** |
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| 172 | * |
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| 173 | * Makes the select FOR UPDATE (or not). |
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| 174 | * |
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| 175 | * @param bool $enable Whether or not the SELECT is FOR UPDATE (default |
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| 176 | * true). |
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| 177 | * |
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| 178 | * @return $this |
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| 179 | * |
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| 180 | */ |
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| 181 | 25 | public function forUpdate($enable = true) |
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| 186 | |||
| 187 | /** |
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| 188 | * |
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| 189 | * Makes the select DISTINCT (or not). |
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| 190 | * |
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| 191 | * @param bool $enable Whether or not the SELECT is DISTINCT (default |
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| 192 | * true). |
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| 193 | * |
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| 194 | * @return $this |
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| 195 | * |
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| 196 | */ |
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| 197 | 16 | public function distinct($enable = true) |
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| 202 | |||
| 203 | /** |
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| 204 | * |
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| 205 | * Is the select DISTINCT? |
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| 206 | * |
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| 207 | * @return bool |
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| 208 | * |
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| 209 | */ |
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| 210 | 10 | public function isDistinct() |
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| 214 | |||
| 215 | /** |
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| 216 | * |
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| 217 | * Adds columns to the query. |
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| 218 | * |
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| 219 | * Multiple calls to cols() will append to the list of columns, not |
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| 220 | * overwrite the previous columns. |
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| 221 | * |
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| 222 | * @param array $cols The column(s) to add to the query. The elements can be |
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| 223 | * any mix of these: `array("col", "col AS alias", "col" => "alias")` |
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| 224 | * |
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| 225 | * @return $this |
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| 226 | * |
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| 227 | */ |
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| 228 | 229 | public function cols(array $cols) |
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| 235 | |||
| 236 | /** |
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| 237 | * |
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| 238 | * Adds a column and alias to the columns to be selected. |
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| 239 | * |
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| 240 | * @param mixed $key If an integer, ignored. Otherwise, the column to be |
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| 241 | * added. |
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| 242 | * |
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| 243 | * @param mixed $val If $key was an integer, the column to be added; |
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| 244 | * otherwise, the column alias. |
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| 245 | * |
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| 246 | * @return null |
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| 247 | * |
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| 248 | */ |
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| 249 | 229 | protected function addCol($key, $val) |
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| 258 | |||
| 259 | /** |
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| 260 | * |
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| 261 | * Adds a column with an alias to the columns to be selected. |
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| 262 | * |
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| 263 | * @param string $spec The column specification: "col alias", |
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| 264 | * "col AS alias", or something else entirely. |
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| 265 | * |
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| 266 | * @return null |
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| 267 | * |
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| 268 | */ |
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| 269 | 219 | protected function addColWithAlias($spec) |
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| 284 | |||
| 285 | /** |
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| 286 | * |
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| 287 | * Remove a column via its alias. |
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| 288 | * |
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| 289 | * @param string $alias The column to remove |
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| 290 | * |
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| 291 | * @return bool |
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| 292 | * |
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| 293 | */ |
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| 294 | 15 | public function removeCol($alias) |
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| 310 | |||
| 311 | /** |
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| 312 | * |
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| 313 | * Has the column or alias been added to the query? |
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| 314 | * |
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| 315 | * @param string $alias The column or alias to look for |
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| 316 | * |
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| 317 | * @return bool |
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| 318 | * |
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| 319 | */ |
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| 320 | 5 | public function hasCol($alias) |
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| 324 | |||
| 325 | /** |
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| 326 | * |
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| 327 | * Does the query have any columns in it? |
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| 328 | * |
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| 329 | * @return bool |
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| 330 | * |
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| 331 | */ |
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| 332 | 5 | public function hasCols() |
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| 336 | |||
| 337 | /** |
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| 338 | * |
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| 339 | * Returns a list of columns. |
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| 340 | * |
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| 341 | * @return array |
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| 342 | * |
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| 343 | */ |
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| 344 | 15 | public function getCols() |
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| 348 | |||
| 349 | /** |
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| 350 | * |
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| 351 | * Tracks table references. |
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| 352 | * |
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| 353 | * @param string $type FROM, JOIN, etc. |
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| 354 | * |
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| 355 | * @param string $spec The table and alias name. |
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| 356 | * |
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| 357 | * @return null |
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| 358 | * |
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| 359 | * @throws Exception when the reference has already been used. |
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| 360 | * |
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| 361 | */ |
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| 362 | 154 | protected function addTableRef($type, $spec) |
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| 378 | |||
| 379 | /** |
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| 380 | * |
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| 381 | * Adds a FROM element to the query; quotes the table name automatically. |
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| 382 | * |
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| 383 | * @param string $spec The table specification; "foo" or "foo AS bar". |
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| 384 | * |
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| 385 | * @return $this |
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| 386 | * |
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| 387 | */ |
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| 388 | 144 | public function from($spec) |
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| 393 | |||
| 394 | /** |
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| 395 | * |
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| 396 | * Adds a raw unquoted FROM element to the query; useful for adding FROM |
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| 397 | * elements that are functions. |
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| 398 | * |
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| 399 | * @param string $spec The table specification, e.g. "function_name()". |
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| 400 | * |
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| 401 | * @return $this |
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| 402 | * |
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| 403 | */ |
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| 404 | 5 | public function fromRaw($spec) |
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| 409 | |||
| 410 | /** |
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| 411 | * |
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| 412 | * Adds to the $from property and increments the key count. |
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| 413 | * |
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| 414 | * @param string $spec The table specification. |
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| 415 | * |
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| 416 | * @return $this |
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| 417 | * |
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| 418 | */ |
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| 419 | 154 | protected function addFrom($spec) |
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| 425 | |||
| 426 | /** |
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| 427 | * |
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| 428 | * Adds an aliased sub-select to the query. |
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| 429 | * |
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| 430 | * @param string|Select $spec If a Select object, use as the sub-select; |
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| 431 | * if a string, the sub-select string. |
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| 432 | * |
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| 433 | * @param string $name The alias name for the sub-select. |
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| 434 | * |
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| 435 | * @return $this |
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| 436 | * |
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| 437 | */ |
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| 438 | 15 | public function fromSubSelect($spec, $name) |
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| 445 | |||
| 446 | /** |
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| 447 | * |
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| 448 | * Formats a sub-SELECT statement, binding values from a Select object as |
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| 449 | * needed. |
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| 450 | * |
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| 451 | * @param string|SelectInterface $spec A sub-SELECT specification. |
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| 452 | * |
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| 453 | * @param string $indent Indent each line with this string. |
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| 454 | * |
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| 455 | * @return string The sub-SELECT string. |
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| 456 | * |
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| 457 | */ |
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| 458 | 25 | protected function subSelect($spec, $indent) |
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| 468 | |||
| 469 | /** |
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| 470 | * |
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| 471 | * Adds a JOIN table and columns to the query. |
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| 472 | * |
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| 473 | * @param string $join The join type: inner, left, natural, etc. |
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| 474 | * |
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| 475 | * @param string $spec The table specification; "foo" or "foo AS bar". |
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| 476 | * |
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| 477 | * @param string $cond Join on this condition. |
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| 478 | * |
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| 479 | * @param array $bind Values to bind to ?-placeholders in the condition. |
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| 480 | * |
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| 481 | * @return $this |
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| 482 | * |
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| 483 | * @throws Exception |
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| 484 | * |
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| 485 | */ |
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| 486 | 45 | public function join($join, $spec, $cond = null, array $bind = array()) |
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| 495 | |||
| 496 | /** |
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| 497 | * |
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| 498 | * Fixes a JOIN condition to quote names in the condition and prefix it |
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| 499 | * with a condition type ('ON' is the default and 'USING' is recognized). |
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| 500 | * |
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| 501 | * @param string $cond Join on this condition. |
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| 502 | * |
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| 503 | * @param array $bind Values to bind to ?-placeholders in the condition. |
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| 504 | * |
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| 505 | * @return string |
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| 506 | * |
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| 507 | */ |
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| 508 | 55 | protected function fixJoinCondition($cond, array $bind) |
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| 527 | |||
| 528 | /** |
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| 529 | * |
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| 530 | * Adds a INNER JOIN table and columns to the query. |
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| 531 | * |
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| 532 | * @param string $spec The table specification; "foo" or "foo AS bar". |
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| 533 | * |
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| 534 | * @param string $cond Join on this condition. |
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| 535 | * |
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| 536 | * @param array $bind Values to bind to ?-placeholders in the condition. |
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| 537 | * |
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| 538 | * @return $this |
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| 539 | * |
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| 540 | * @throws Exception |
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| 541 | * |
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| 542 | */ |
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| 543 | 10 | public function innerJoin($spec, $cond = null, array $bind = array()) |
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| 547 | |||
| 548 | /** |
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| 549 | * |
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| 550 | * Adds a LEFT JOIN table and columns to the query. |
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| 551 | * |
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| 552 | * @param string $spec The table specification; "foo" or "foo AS bar". |
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| 553 | * |
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| 554 | * @param string $cond Join on this condition. |
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| 555 | * |
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| 556 | * @param array $bind Values to bind to ?-placeholders in the condition. |
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| 557 | * |
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| 558 | * @return $this |
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| 559 | * |
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| 560 | * @throws Exception |
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| 561 | * |
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| 562 | */ |
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| 563 | 10 | public function leftJoin($spec, $cond = null, array $bind = array()) |
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| 567 | |||
| 568 | /** |
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| 569 | * |
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| 570 | * Adds a JOIN to an aliased subselect and columns to the query. |
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| 571 | * |
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| 572 | * @param string $join The join type: inner, left, natural, etc. |
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| 573 | * |
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| 574 | * @param string|Select $spec If a Select |
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| 575 | * object, use as the sub-select; if a string, the sub-select |
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| 576 | * command string. |
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| 577 | * |
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| 578 | * @param string $name The alias name for the sub-select. |
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| 579 | * |
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| 580 | * @param string $cond Join on this condition. |
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| 581 | * |
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| 582 | * @param array $bind Values to bind to ?-placeholders in the condition. |
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| 583 | * |
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| 584 | * @return $this |
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| 585 | * |
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| 586 | * @throws Exception |
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| 587 | * |
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| 588 | */ |
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| 589 | 20 | public function joinSubSelect($join, $spec, $name, $cond = null, array $bind = array()) |
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| 601 | |||
| 602 | /** |
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| 603 | * |
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| 604 | * Adds the JOIN to the right place, given whether or not a FROM has been |
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| 605 | * specified yet. |
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| 606 | * |
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| 607 | * @param string $spec The JOIN clause. |
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| 608 | * |
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| 609 | * @return $this |
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| 610 | * |
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| 611 | */ |
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| 612 | 55 | protected function addJoin($spec) |
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| 618 | |||
| 619 | /** |
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| 620 | * |
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| 621 | * Adds grouping to the query. |
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| 622 | * |
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| 623 | * @param array $spec The column(s) to group by. |
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| 624 | * |
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| 625 | * @return $this |
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| 626 | * |
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| 627 | */ |
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| 628 | 5 | public function groupBy(array $spec) |
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| 635 | |||
| 636 | /** |
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| 637 | * |
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| 638 | * Adds a HAVING condition to the query by AND. If the condition has |
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| 639 | * ?-placeholders, additional arguments to the method will be bound to |
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| 640 | * those placeholders sequentially. |
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| 641 | * |
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| 642 | * @param string $cond The HAVING condition. |
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| 643 | * |
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| 644 | * @param array ...$bind arguments to bind to placeholders |
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| 645 | * |
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| 646 | * @return $this |
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| 647 | * |
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| 648 | */ |
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| 649 | 10 | public function having($cond, ...$bind) |
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| 654 | |||
| 655 | /** |
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| 656 | * |
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| 657 | * Adds a HAVING condition to the query by AND. If the condition has |
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| 658 | * ?-placeholders, additional arguments to the method will be bound to |
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| 659 | * those placeholders sequentially. |
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| 660 | * |
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| 661 | * @param string $cond The HAVING condition. |
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| 662 | * |
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| 663 | * @param array ...$bind arguments to bind to placeholders |
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| 664 | * |
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| 665 | * @return $this |
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| 666 | * |
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| 667 | * @see having() |
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| 668 | * |
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| 669 | */ |
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| 670 | 5 | public function orHaving($cond, ...$bind) |
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| 675 | |||
| 676 | /** |
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| 677 | * |
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| 678 | * Sets the limit and count by page number. |
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| 679 | * |
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| 680 | * @param int $page Limit results to this page number. |
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| 681 | * |
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| 682 | * @return $this |
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| 683 | * |
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| 684 | */ |
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| 685 | 30 | public function page($page) |
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| 691 | |||
| 692 | /** |
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| 693 | * |
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| 694 | * Updates the limit and offset values when changing pagination. |
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| 695 | * |
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| 696 | * @return null |
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| 697 | * |
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| 698 | */ |
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| 699 | 30 | protected function setPagingLimitOffset() |
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| 708 | |||
| 709 | /** |
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| 710 | * |
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| 711 | * Returns the page number being selected. |
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| 712 | * |
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| 713 | * @return int |
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| 714 | * |
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| 715 | */ |
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| 716 | 5 | public function getPage() |
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| 720 | |||
| 721 | /** |
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| 722 | * |
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| 723 | * Takes the current select properties and retains them, then sets |
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| 724 | * UNION for the next set of properties. |
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| 725 | * |
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| 726 | * @return $this |
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| 727 | * |
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| 728 | */ |
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| 729 | 15 | public function union() |
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| 735 | |||
| 736 | /** |
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| 737 | * |
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| 738 | * Takes the current select properties and retains them, then sets |
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| 739 | * UNION ALL for the next set of properties. |
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| 740 | * |
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| 741 | * @return $this |
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| 742 | * |
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| 743 | */ |
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| 744 | 5 | public function unionAll() |
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| 750 | |||
| 751 | /** |
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| 752 | * |
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| 753 | * Clears the current select properties; generally used after adding a |
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| 754 | * union. |
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| 755 | * |
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| 756 | * @return null |
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| 757 | * |
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| 758 | */ |
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| 759 | 20 | public function reset() |
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| 773 | |||
| 774 | /** |
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| 775 | * |
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| 776 | * Resets the columns on the SELECT. |
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| 777 | * |
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| 778 | * @return $this |
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| 779 | * |
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| 780 | */ |
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| 781 | 20 | public function resetCols() |
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| 786 | |||
| 787 | /** |
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| 788 | * |
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| 789 | * Resets the FROM and JOIN clauses on the SELECT. |
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| 790 | * |
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| 791 | * @return $this |
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| 792 | * |
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| 793 | */ |
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| 794 | 20 | public function resetTables() |
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| 802 | |||
| 803 | /** |
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| 804 | * |
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| 805 | * Resets the WHERE clause on the SELECT. |
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| 806 | * |
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| 807 | * @return $this |
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| 808 | * |
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| 809 | */ |
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| 810 | 20 | public function resetWhere() |
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| 815 | |||
| 816 | /** |
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| 817 | * |
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| 818 | * Resets the GROUP BY clause on the SELECT. |
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| 819 | * |
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| 820 | * @return $this |
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| 821 | * |
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| 822 | */ |
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| 823 | 20 | public function resetGroupBy() |
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| 828 | |||
| 829 | /** |
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| 830 | * |
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| 831 | * Resets the HAVING clause on the SELECT. |
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| 832 | * |
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| 833 | * @return $this |
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| 834 | * |
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| 835 | */ |
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| 836 | 20 | public function resetHaving() |
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| 841 | |||
| 842 | /** |
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| 843 | * |
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| 844 | * Resets the ORDER BY clause on the SELECT. |
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| 845 | * |
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| 846 | * @return $this |
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| 847 | * |
||
| 848 | */ |
||
| 849 | 20 | public function resetOrderBy() |
|
| 854 | |||
| 855 | /** |
||
| 856 | * |
||
| 857 | * Resets the UNION and UNION ALL clauses on the SELECT. |
||
| 858 | * |
||
| 859 | * @return $this |
||
| 860 | * |
||
| 861 | */ |
||
| 862 | 5 | public function resetUnions() |
|
| 867 | |||
| 868 | /** |
||
| 869 | * |
||
| 870 | * Builds this query object into a string. |
||
| 871 | * |
||
| 872 | * @return string |
||
| 873 | * |
||
| 874 | */ |
||
| 875 | 189 | protected function build() |
|
| 901 | |||
| 902 | /** |
||
| 903 | * |
||
| 904 | * Sets a limit count on the query. |
||
| 905 | * |
||
| 906 | * @param int $limit The number of rows to select. |
||
| 907 | * |
||
| 908 | * @return $this |
||
| 909 | * |
||
| 910 | */ |
||
| 911 | 35 | public function limit($limit) |
|
| 920 | |||
| 921 | /** |
||
| 922 | * |
||
| 923 | * Sets a limit offset on the query. |
||
| 924 | * |
||
| 925 | * @param int $offset Start returning after this many rows. |
||
| 926 | * |
||
| 927 | * @return $this |
||
| 928 | * |
||
| 929 | */ |
||
| 930 | 35 | public function offset($offset) |
|
| 939 | |||
| 940 | /** |
||
| 941 | * |
||
| 942 | * Adds a column order to the query. |
||
| 943 | * |
||
| 944 | * @param array $spec The columns and direction to order by. |
||
| 945 | * |
||
| 946 | * @return $this |
||
| 947 | * |
||
| 948 | */ |
||
| 949 | 5 | public function orderBy(array $spec) |
|
| 953 | } |
||
| 954 |
In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: