prepare($sql);判断执行准备好的sql语句，成功返回true，失败返回falseif($shuzu->execute()){   执行成功有四种方法1逐行取出数据var_dump($stm->fetch());2取出所有的数据var_dump($stm->fetchAll(PDO::FETCH_OBJ));3取出一列var_dump($stm->fetchColumn(1));4 返回对象var_dump($stm->fetchObject());}else{  echo"执行有误";}?>增加更简便的方法
     prepare($sql);造数组$attr  = array("p101","很快");$attr  = array("code"=>"p103","name"=>"shj");执行if($stm->execute($_POST)){	echo "添加成功";}else{	echo "添加失败";}?>