php pdo 开发mysql事务（行锁）

<html>
     <body>
         <?php
             #数据库连接
             $dbtype = 'mysql';
             $host = 'localhost';
             $db = 'test';
             $user = 'root';
             $psw = 'china0913';

             $dsn = $dbtype . ':host=' . $host . ';' . 'dbname=' . $db;

             try {
                 $dbh = new PDO($dsn, $user, $psw, array(PDO::ATTR_PERSISTENT=>true));
                 echo '连接成功<br>';
             } catch(Exception $e) {
                 die('Connect Failed Message: ' . $e->getMessage());
             }

             #使用query函数查询
             $sql = 'SELECT * FROM user';
             $query = $dbh->query($sql);
             $query->setFetchMode(PDO::FETCH_ASSOC);    //设置结果集返回格式,此处为关联数组,即不包含index下标
             $rs = $query->fetchAll();
             var_dump($rs);

             #使用exec函数进行INSERT,UPDATE,DELETE,结果返回受影响的行数
             $sql = 'INSERT INTO user (`userName`, `userPassword`, `userAge`) SELECT (MAX(userId) + 1), \'123456\', 18 FROM user';    //插入一行用户数据,其中userName使用userId最大值+1
             // $rs = $dbh->exec($sql);
             // var_dump($rs) . '<br>';

             #使用prepareStatement进行CURD
             $sql = 'SELECT * FROM user WHERE userId = ?';
             $stmt = $dbh->prepare($sql);
             $stmt->bindParam(1, $userId);    //绑定第一个参数值
             $userId = 1;

             $stmt->execute();
             $stmt->setFetchMode(PDO::FETCH_ASSOC);
             $rs = $stmt->fetchAll();
             var_dump($rs);

             #使用事务
             try {
                 $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);    //设置错误模式,发生错误时抛出异常
                 $dbh->beginTransaction();
                 $sql1 = 'SELECT bookNum FROM book WHERE bookId = ? FOR UPDATE';    //此处加上行锁,可以对bookNum做一些判断,bookNum>1,才做下一步更新操作
                 $sql2 = 'UPDATE book SET bookNum=bookNum-1 WHERE bookId = ?';    //加上行锁后,如果user1在买书,并且user1的买书过程没有结束,user2就不能执行SELECT查询书籍数量的操作,这样就保证了不会出现只有1本书,却两个人同时买的状况
                 $stmt1 = $dbh->prepare($sql1);
                 $stmt2 = $dbh->prepare($sql2);
                 $stmt1->bindParam(1, $userId);      //应该是bookId
                 $stmt2->bindParam(1, $userId);      //应该是bookId
                 $userId = 1;      //应该是bookId
                 $stmt1->execute();
                 $stmt2->execute();
                 $dbh->commit();
             } catch(Exception $e) {
                 $dbh->rollBack();
                 die('Transaction Error Message: ' . $e->getMessage());
             }
         ?>
     </body>
</html>

php pdo 开发mysql事务（行锁）

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