<?php//1.造PDO对象$dsn ="mysql:dbname=mydb;host=localhost";//数据库类型:dbname=数据库名称;host=链接的ip或本机$pdo =new PDO($dsn,"root","root");//$dsn,帐号，密码//2.写SQL语句$sql ="select * from info";  $sql ="insert into info values('004','王六','男','n007','1994-02-11')";//3.执行SQL语句$stm = $pdo->query($sql); //查询语句用query,返回的是结果$arr = $pdo->exec($sql);//增删改用exec，返回的是执行的行数//4.从PDOStatement对象里面读数据$arr =$stm->fetch(PDO::FETCH_NUM);//默认不选为PDO::FETCH_BOTH  fetch为选择一条数据$arr = $stm->fetchAll(PDO::FETCH_BOTH);//fetchAll为全选//事务类型:即要不全部都通过，要不全部失败，可以参考淘宝购物，必须同时满足扣款，减去库存和添加订单三项条件，缺一不可//beginTransation 启动事务//commit 提交事务//rollback 回滚:返回到启动事务之前//1.造PDO对象$dsn ="mysql:dbname=mydb;host=localhost";$pdo =new PDO($dsn,"root","root");//2.将PDO的错误类型设置为异常模式$pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);try  //尝试运行,包含从开启事务到提交事务{    //开启事务    $pdo->beginTransaction();    $sql1 = "insert into info values('004','进口','男','n008','1994-05-11')";    $sql2 = "insert into info values('005','审核','男','n009','1994-07-11')";    $sql3 = "insert into info values('006','姐我','男','n0010','1994-08-11')";        $pdo->exec($sql1);    $pdo->exec($sql2);    $pdo->exec($sql3);        //提交事务    $pdo->commit();}    catch(Exception $e)    {        //回滚操作        $pdo->rollBack();            }        final    {        //最终执行，无论有没有异常出现，该代码都会执行    }    ?>