如何使用游标创建存储过程以通过验证将数据从一个表移动到另一表（Mysql）

Question

I have to move data from resource table to event table to remove resource table. Consider, Table schemas as follows, mysql> desc event

+-----------------+--------------+------+-----+---------+----------------+
| Field           | Type         | Null | Key | Default | Extra          |
+-----------------+--------------+------+-----+---------+----------------+
| event_id        | bigint(20)   | NO   | PRI | NULL    | auto_increment |
| path            | varchar(255) | YES  |     | NULL    |                |
+-----------------+--------------+------+-----+---------+----------------+

mysql> desc resource;

+--------------------+--------------+------+-----+---------+----------------+
| Field              | Type         | Null | Key | Default | Extra          |
+--------------------+--------------+------+-----+---------+----------------+
| resource_id        | bigint(20)   | NO   | PRI | NULL    | auto_increment |
| jcr_id             | varchar(500) | YES  |     | NULL    |                |
+--------------------+--------------+------+-----+---------+----------------+

event path contain jcr_id or resource_id, if it contain jcr_id then entry from resouce table else update event path value with jcr_id and then delete.

Consider following Psuedo code while iterating every resource_id,

 result = select event_id from event where path=_resource_id;
 if result is empty 
   delete from resource where resource_id= _resource_id;
 else 
   update event set path=jcr_id where event_id= result;
   delete from resource where resource_id= _resource_id;

Answer 1

Try this.

DELIMITER //
CREATE PROCEDURE `new_procedure` ()
BEGIN
    declare row_min int;
    declare row_max int;
    declare resource_id int;

    select 1, max(resource_id)
    into row_min, row_max
    from resource;

    while row_min <= row_max
    do
        select resource_id into resource_id
        from resource
        where resource_id = row_min;

        -- Iterating for every record. Add your update code here.

        set row_min = row_min + 1;
    end while;
END//
DELIMITER ;