mysql操作类(5)

            } 
        } 
     } 
     //简化插入insert   
     public  function insert($table,$columnName,$value,$url=''){ 
          if($this->query("insert into $table ($columnName) values ($value)")){ 
            if(!emptyempty($url)){ 
                $this->Get_admin_msg($url,'添加成功'); 
            } 
          } 
         
     } 
     //简化更新update  
     public function update($table,$mod_content,$condition,$url=''){ 
        if($this->query("update $table set $mod_content where $condition")){ 
            if(!emptyempty($url)){ 
                $this->Get_admin_msg($url); 
            } 
        } 
     } 
     //取得上一步insert操作的id  
     public  function insert_id(){ 
        return  mysql_insert_id(); 
     } 
     //指向确定的一条数据记录  
     public  function db_data_seek($id){ 
        if($id>0){ 
            $id=$id-1; 
        } 
        if(!@mysql_data_seek($this->result,$id)){ 
            $this->show_error("sql语句有误：","指定的数据为空"); 
        } 
        return $this->result; 
     } 
     //根据select查询结果计算结果集条数  
     public function db_num_rows(){ 
        if($this->result=null){ 
            if($this->show_error){