/** * 构造最终查询语句 * * @return string */ public function __toString() { switch ($this->_sqlPreBuild['action']) { case Db::SELECT: return $this->_adapter->parseSelect($this->_sqlPreBuild); case Db::INSERT: return 'INSERT INTO ' . $this->_sqlPreBuild['table'] . '(' . implode(' , ', array_keys($this->_sqlPreBuild['rows'])) . ')' . ' VALUES ' . '(' . implode(' , ', array_values($this->_sqlPreBuild['rows'])) . ')' . $this->_sqlPreBuild['limit']; case Db::DELETE: return 'DELETE FROM ' . $this->_sqlPreBuild['table'] . $this->_sqlPreBuild['where']; case Db::UPDATE: $columns = array(); if (isset($this->_sqlPreBuild['rows'])) { foreach ($this->_sqlPreBuild['rows'] as $key => $val) { $columns[] = "{$key} = {$val}"; } } return 'UPDATE ' . $this->_sqlPreBuild['table'] . ' SET ' . implode(' , ', $columns) . $this->_sqlPreBuild['where']; default: return NULL; } }