返回多个值

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INOUTOUT参数的存储过程。

如果您不熟悉INPUTOUT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

IN参数之外,存储过程还需要4个额外的OUT参数:shipped, canceled, resolveddisputed。 在存储过程中,使用带有COUNT函数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);

@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。

Last updated