mysql存储过程之返回多个值的方法示例

本文实例讲述了mysql/' target='_blank'>mysql存储过程之返回多个值的方法。分享给大家供大家参考，具体如下：

MySQL存储函数只返回一个值。要开发返回多个值的存储过程，需要使用带有INOUT或OUT参数的存储过程。咱们先来看一个orders表它的结构：

mysql> desc orders;+----------------+-------------+------+-----+---------+-------+| Field     | Type    | Null | Key | Default | Extra |+----------------+-------------+------+-----+---------+-------+| orderNumber  | int(11)   | NO  | PRI | NULL  |    || orderDate   | date    | NO  |   | NULL  |    || requiredDate  | date    | NO  |   | NULL  |    || shippedDate  | date    | YES |   | NULL  |    || status     | varchar(15) | NO  |   | NULL  |    || comments    | text    | YES |   | NULL  |    || customerNumber | int(11)   | NO  | MUL | NULL  |    |+----------------+-------------+------+-----+---------+-------+7 rows in set

然后嘞，咱们来看一个存储过程，它接受客户编号，并返回发货(shipped)，取消(canceled)，解决(resolved)和争议(disputed)的订单总数：

DELIMITER $$CREATE PROCEDURE get_order_by_cust( IN cust_no INT, OUT shipped INT, OUT canceled INT, OUT resolved INT, OUT disputed INT)BEGIN -- shipped SELECT      count(*) INTO shipped    FROM      orders    WHERE      customerNumber = cust_no        AND status = 'Shipped'; -- canceled SELECT      count(*) INTO canceled    FROM      orders    WHERE      customerNumber = cust_no        AND status = 'Canceled'; -- resolved SELECT      count(*) INTO resolved    FROM      orders    WHERE      customerNumber = cust_no        AND status = 'Resolved'; -- disputed SELECT      count(*) INTO disputed    FROM      orders    WHERE      customerNumber = cust_no        AND status = 'Disputed';END

其实，除IN参数之外，存储过程还需要4个额外的OUT参数：shipped, canceled, resolved 和 disputed。 在存储过程中，使用带有count函数的select语句根据订单状态获取相应的订单总数，并将其分配给相应的参数。按着上面的sql，我们如果要使用get_order_by_cust存储过程，可以传递客户编号和四个用户定义的变量来获取输出值。执行存储过程后，我们再使用SELECT语句输出变量值：

+----------+-----------+-----------+-----------+| @shipped | @canceled | @resolved | @disputed |+----------+-----------+-----------+-----------+|    22 |     0 |     1 |     1 |+----------+-----------+-----------+-----------+1 row in set

结合实际应用，我们再来看下从PHP程序中调用返回多个值的存储过程：

<?php/** * Call stored procedure that return multiple values * @param $customerNumber */function call_sp($customerNumber){  try {    $pdo = new PDO("mysql:host=localhost;dbname=yiibaidb", 'root', '123456');    // execute the stored procedure    $sql = 'CALL get_order_by_cust(:no,@shipped,@canceled,@resolved,@disputed)';    $stmt = $pdo->prepare($sql);    $stmt->bindParam(':no', $customerNumber, PDO::PARAM_INT);    $stmt->execute();    $stmt->closeCursor();    // execute the second query to get values from OUT parameter    $r = $pdo->query("SELECT @shipped,@canceled,@resolved,@disputed")         ->fetch(PDO::FETCH_ASSOC);    if ($r) {      printf('Shipped: %d, Canceled: %d, Resolved: %d, Disputed: %d',        $r['@shipped'],        $r['@canceled'],        $r['@resolved'],        $r['@disputed']);    }  } catch (PDOException $pe) {    die("Error occurred:" . $pe->getMessage());  }}call_sp(141);

上述代码中，在@符号之前的用户定义的变量与数据库连接相关联，因此它们可用于在调用之间进行访问。

好啦，本次分享就到这里了。

更多关于MySQL相关内容感兴趣的读者可查看本站专题：《MySQL存储过程技巧大全》、《MySQL常用函数大汇总》、《MySQL日志操作技巧大全》、《MySQL事务操作技巧汇总》及《MySQL数据库锁相关技巧汇总》

希望本文所述对大家MySQL数据库计有所帮助。