php中实现用数组妩媚地生成要执行的sql语句

/**   * [array_to_sql 根据数组key和value拼接成需要的sql]   * @param [type] $array  [key, value结构数组]   * @param string $type  [sql类型insert,update]   * @param array $exclude [排除的字段]   * @return [string]     [返回拼接好的sql]   */  function array_to_sql($array, $type='insert', $exclude = array()){        $sql = '';    if(count($array) > 0){      foreach ($exclude as $exkey) {        unset($array[$exkey]);//剔除不要的key      }      if('insert' == $type){        $keys = array_keys($array);        $values = array_values($array);        $col = implode("`, `", $keys);        $val = implode("', '", $values);        $sql = "(`$col`) values('$val')";      }else if('update' == $type){        $tempsql = '';        $temparr = array();        foreach ($array as $key => $value) {          $tempsql = "'$key' = '$value'";          $temparr[] = $tempsql;        }        $sql = implode(",", $temparr);      }    }    return $sql;  }