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Create a MySQL stored procedure to get rows from a table using a cursor?

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Release: 2023-09-16 21:45:07
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创建一个 MySQL 存储过程,使用游标从表中获取行?

The following is a stored procedure that gets the records from the name column of the table "student_info" which has the following data -

mysql> Select * from Student_info;
+-----+---------+------------+------------+
| id  | Name    | Address    | Subject    |
+-----+---------+------------+------------+
| 101 | YashPal | Amritsar   | History    |
| 105 | Gaurav  | Chandigarh | Literature |
| 125 | Raman   | Shimla     | Computers  |
| 127 | Ram     | Jhansi     | Computers  |
+-----+---------+------------+------------+
4 rows in set (0.00 sec)

mysql> Delimiter //

mysql> CREATE PROCEDURE cursor_defined(OUT val VARCHAR(20))
    -> BEGIN
    -> DECLARE a,b VARCHAR(20);
    -> DECLARE cur_1 CURSOR for SELECT Name from student_info;
    -> DECLARE CONTINUE HANDLER FOR NOT FOUND
    -> SET b = 1;
    -> OPEN CUR_1;
    -> REPEAT
    -> FETCH CUR_1 INTO a;
    -> UNTIL b = 1
    -> END REPEAT;
    -> CLOSE CUR_1;
    -> SET val = a;
    -> END//
Query OK, 0 rows affected (0.04 sec)

mysql> Delimiter ;
mysql> Call cursor_defined2(@val);
Query OK, 0 rows affected (0.11 sec)

mysql> Select @val;
+------+
| @val |
+------+
| Ram |
+------+
1 row in set (0.00 sec)
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From the above result set , we can see that the value of the val parameter is "Ram" because it is the last value of the "Name" column.

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source:tutorialspoint.com
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