在本教程中,您将学习如何编写/开发返回多个值的存储过程。
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。
如果您不熟悉INPUT或OUT参数的用法,请查看存储过程参数教程的详细信息。
返回多个值的存储过程示例
我们来看看示例数据库(yiibaidb)中的orders表。
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 |
以下存储过程接受客户编号,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 |
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。
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,使用SELECT语句输出变量值。
+----------+-----------+-----------+-----------+
| @shipped | @canceled | @resolved | @disputed
|
+----------+-----------+-----------+-----------+
| 22 | 0 | 1 | 1 |
+----------+-----------+-----------+-----------+
1 row in set |
从PHP调用返回多个值的存储过程
以下代码片段显示如何从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); |
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。
在本教程中,我们向您展示了如何编写/开发返回多个值的存储过程以及如何从PHP调用它。 |