本篇文章將介紹存儲過程返回多個結果集時是什么結果，希望給大家以參考作用。
mysql存儲函數只返回一個值。要開發返回多個值的存儲過程，需要使用帶有INOUT或OUT參數的存儲過程。
咱們先來看一個orders表它的結構：
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，咱們來看一個存儲過程，它接受客戶編號，并返回發貨(shipped)，取消(canceled)，解決(resolved)和爭議(disputed)的訂單總數(多個結果集)：
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
其實，除IN參數之外，存儲過程還需要4個額外的OUT參數：shipped, canceled, resolved 和 disputed。 在存儲過程中，使用帶有count函數的select語句根據訂單狀態獲取相應的訂單總數，并將其分配給相應的參數。按著上面的sql，我們如果要使用get_order_by_cust存儲過程，可以傳遞客戶編號和四個用戶定義的變量來獲取輸出值。執行存儲過程后，我們再使用SELECT語句輸出變量值：
+----------+-----------+-----------+-----------+ | @shipped | @canceled | @resolved | @disputed | +----------+-----------+-----------+-----------+ | 22 | 0 | 1 | 1 | +----------+-----------+-----------+-----------+ 1 row in set
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