<?php    /* pdo 学习 */    $dsn    = ‘mysql:host=localhost;dbname=cswl‘;//构建连接dsn    $db     = new pdo($dsn,‘root‘,‘‘);//实例化pdo【第二个参数是用户名，第三个为密码】    #.查询    $obj    = $db->prepare("show tables;");//准备预处理sql语句    $obj->execute();//执行预处理语句    $obj->fetchALL(PDO::FETCH_ASSOC);//获取结果集    #.插入    $obj    = null;    $sql    = "insert into level_class               (sales_id,levelName,gameName,addTime,status) VALUES (?,?,?,?,?)";    $obj    = $db->prepare($sql);//准备预处理sql语句    $obj->execute(array(1,‘赤天‘,‘赤天‘,time(),1));//执行一条插入语句    #.删除    $obj    = null;    $sql    = "delete from level_class";    $obj    = $db->prepare($sql);    $obj->execute();?>