如何建立一個MySQL預存程序，從MySQL表傳回多個值？

我們可以建立一個帶有 IN和OUT參數的預存過程，從MySQL表中取得多個值。為了讓它理解，我們以一個名為「student_info」的表為例，該表包含以下資料−

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)

現在，透過建立以下名為'select_studentinfo'的過程，我們可以透過提供'id '的值從'student_info'表中選擇值−

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 //
Query OK, 0 rows affected (0.03 sec)

在上面的查詢中，除了1個IN參數外，還有4個OUT參數。現在，按照我們要提供的條件值呼叫該過程，如下所示 −

mysql> DELIMITER ; //
mysql> CALL Select_studentinfo(110, @p_name, @p_address, @p_subject);
Query OK, 1 row affected (0.06 sec)

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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