如何创建从MySQL表返回多个值的MySQL存储过程?
我们可以使用 IN和OUT参数创建一个存储过程,以从MySQL表中获取多个值。为了理解它,我们以一个名为“ student_info”的表为例,该表包含以下数据:
mysql> Select * from student_info;+------+---------+------------+------------+
| id | Name | Address | Subject |
+------+---------+------------+------------+
| 101 | YashPal | Amritsar | History |
| 105 | Gaurav | Jaipur | Literature |
| 110 | Rahul | Chandigarh | History |
| 125 | Raman | Bangalore | Computers |
+------+---------+------------+------------+
4 rows in set (0.01 sec)
现在,通过如下创建名为“ select_studentinfo”的过程,我们可以通过提供“ id”的值从“ student_info”表中选择值-
mysql> DELIMITER // ;mysql> Create Procedure Select_studentinfo ( IN p_id INT, OUT p_name varchar(20),OUT p_address varchar(20), OUT p_subject varchar(20))
-> BEGIN
-> SELECT name, address, subject INTO p_name, p_address, p_subject
-> FROM student_info
-> WHERE id = p_id;
-> END //
在上面的查询中,连同1IN参数一起,它也取4个OUT参数。现在,使用我们想要提供的值调用该过程,如下所示:
mysql> DELIMITER ; //mysql> CALL Select_studentinfo(110, @p_name, @p_address, @p_subject);
mysql> Select @p_name AS Name,@p_Address AS Address, @p_subject AS Subject;
+--------+------------+-----------+
| Name | Address | Subject |
+--------+------------+-----------+
| Rahul | Chandigarh | History |
+--------+------------+-----------+
1 row in set (0.00 sec)
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