一个简单记事本php操作mysql辅助类创建

//SqlHelper.class.php<?phpclass SqlHelper{    public $conn;    public $host="localhost";    public $user="root";    public $passwrd="passwd";    public $db="notebook";    function __construct(){        $this->conn=mysql_connect($this->host,$this->user,$this->passwrd);        if(!$this->conn){           die("连接失败".mysql_error());         }        mysql_select_db($this->db);        mysql_query("set names utf8");    }    //增删改    function execute_dml($sql){       $b=mysql_query($sql);       if(!$b){           die("操作失败".mysql_error());       }else if(mysql_affected_rows($this->conn)>0){           return 1;       }else{           return 2;       }    }    //查询，多条结果    function execute_dql($sql){        $arr=array();        $res=mysql_query($sql);        $i=0;        while($row=mysql_fetch_assoc($res)){            $arr[$i++]=$row;        }        mysql_free_result($res);        return $arr;    }    //查询，单条结果    function execute_dql2($sql){        $res=mysql_query($sql);        return $res;    }    function conn_close(){        if(!empty($this->conn)){            mysql_close($this->conn);        }    }  }