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：
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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：
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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：
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+----------+-----------+-----------+-----------+| @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：
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<?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); |
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。
希望本文所述对大家MySQL数据库计有所帮助。
原文链接：https://blog.csdn.net/luyaran/article/details/80968547
