Db::parseWhere PHP Method

    protected function parseWhere($where)
    {
        $whereStr = '';
        if (is_string($where)) {
            // 直接使用字符串条件
            $whereStr = $where;
        } else {
            // 使用数组条件表达式
            if (array_key_exists('_logic', $where)) {
                // 定义逻辑运算规则 例如 OR XOR AND NOT
                $operate = ' ' . strtoupper($where['_logic']) . ' ';
                unset($where['_logic']);
            } else {
                // 默认进行 AND 运算
                $operate = ' AND ';
            }
            foreach ($where as $key => $val) {
                $whereStr .= '( ';
                if (0 === strpos($key, '_')) {
                    // 解析特殊条件表达式
                    $whereStr .= $this->parseThinkWhere($key, $val);
                } else {
                    $key = $this->addSpecialChar($key);
                    if (is_array($val)) {
                        if (is_string($val[0])) {
                            if (preg_match('/^(EQ|NEQ|GT|EGT|LT|ELT|NOTLIKE|LIKE)$/i', $val[0])) {
                                // 比较运算
                                $whereStr .= $key . ' ' . $this->comparison[strtolower($val[0])] . ' ' . $this->parseValue($val[1]);
                            } elseif ('exp' == strtolower($val[0])) {
                                // 使用表达式
                                $whereStr .= ' (' . $key . ' ' . $val[1] . ') ';
                            } elseif (preg_match('/IN/i', $val[0])) {
                                // IN 运算
                                $zone = is_array($val[1]) ? implode(',', $this->parseValue($val[1])) : $val[1];
                                $whereStr .= $key . ' ' . strtoupper($val[0]) . ' (' . $zone . ')';
                            } elseif (preg_match('/BETWEEN/i', $val[0])) {
                                // BETWEEN运算
                                $data = is_string($val[1]) ? explode(',', $val[1]) : $val[1];
                                $whereStr .= ' (' . $key . ' BETWEEN ' . $data[0] . ' AND ' . $data[1] . ' )';
                            } else {
                                throw_exception(L('_EXPRESS_ERROR_') . ':' . $val[0]);
                            }
                        } else {
                            $count = count($val);
                            if (in_array(strtoupper(trim($val[$count - 1])), array('AND', 'OR', 'XOR'))) {
                                $rule = strtoupper(trim($val[$count - 1]));
                                $count = $count - 1;
                            } else {
                                $rule = 'AND';
                            }
                            for ($i = 0; $i < $count; $i++) {
                                $data = is_array($val[$i]) ? $val[$i][1] : $val[$i];
                                if ('exp' == strtolower($val[$i][0])) {
                                    $whereStr .= '(' . $key . ' ' . $data . ') ' . $rule . ' ';
                                } else {
                                    $op = is_array($val[$i]) ? $this->comparison[strtolower($val[$i][0])] : '=';
                                    $whereStr .= '(' . $key . ' ' . $op . ' ' . $this->parseValue($data) . ') ' . $rule . ' ';
                                }
                            }
                            $whereStr = substr($whereStr, 0, -4);
                        }
                    } else {
                        //对字符串类型字段采用模糊匹配
                        if (C('DB_LIKE_FIELDS') && preg_match('/(' . C('DB_LIKE_FIELDS') . ')/i', $key)) {
                            $val = '%' . $val . '%';
                            $whereStr .= $key . ' LIKE ' . $this->parseValue($val);
                        } else {
                            $whereStr .= $key . ' = ' . $this->parseValue($val);
                        }
                    }
                }
                $whereStr .= ' )' . $operate;
            }
            $whereStr = substr($whereStr, 0, -strlen($operate));
        }
        return empty($whereStr) ? '' : ' WHERE ' . $whereStr;
    }