<?php$dsn = 'mysql:dbname=test;host=127.0.0.1';$user = 'root';$password = '12345678';$dbh = new PDO($dsn, $user, $password);$dbh->query('set names utf8');if(!$dbh){ exit('连接数据库失败');}$context = $dbh->query("select * from my_test");$res = $context->fetchAll(PDO::FETCH_ASSOC);var_dump($res);$dbh->beginTransaction();$count = $dbh->exec("delete from `my_test` where my_id<150");$dbh->rollback();$dbh->commit();