本文实例讲述了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：

/**

* 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。