mysql存储过程返回多个结果集吗

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(多个结果集)：

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

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