Mysqli操作

<?php
//mysqli数据库通用类
        class Mysqli_Oper
        {
            private $hostname='127.0.0.1';
            private $username='root';
            private $password='52ebook';
            private $dbname='b_work';
            private $conn;
            function __construct()
            {
                $this->conn=new mysqli($this->hostname,$this->username,$this->password,$this->dbname);
                if(mysqli_connect_errno())
                {
                    echo mysqli_connect_error();
                    die;
                }
                $this->conn->set_charset('utf8');
            }
            
            //获取所影响的行数
            function QueryAffected($sql)
            {
                $this->conn->query($sql);
                return $this->conn->affected_rows;
            }
            //查询整个数据集
            function QueryAll($sql,$result_mode='assoc')
            {
                $result=$this->conn->query($sql);
                $table;
                switch($result_mode)
                {
                    case 'assoc':
                    $table=$result->fetch_all(MYSQLI_ASSOC);
                    break;
                    case 'num':
                    $table=$result->fetch_all(MYSQLI_NUM);
                    break;
                    case 'both':
                    $table=$result->fetch_all(MYSQLI_BOTH);
                    break;
                    default:
                    $table=$result->fetch_all(MYSQLI_ASSOC);
                    break;
                }
                return $table;
            }
            //查询第一行数据
            function QueryFirstRow($sql)
            {
                $result=$this->conn->query($sql);
                return $result->fetch_array(MYSQLI_ASSOC);
            }
            //获取上一次插入的id号
            function QueryInsertid($sql)
            {
                $this->conn->query($sql);
                return $this->conn->insert_id;
            }
            //绑定参数，防止sql注入
            function PreExecSql($sql,$par_array)
            {
                $pare=$this->conn->stmt_init();
                $pare->prepare($sql);
                $pare->bind_param("iisi",$a,$b,$c,$d);
                for($n=0;$n<sizeof($par_array);$n++)
                {
                    $a=$par_array[$n][0];
                    $b=$par_array[$n][1];
                    $c=$par_array[$n][2];
                    $d=$par_array[$n][3];
                    $pare->execute();
                }
                $pare->close();
                
            }
            function __destruct()
            {
                $this->conn->close();
            }
        }

?>