在单个mysql查询中将一些金额从一列转移到同一表的另一列

Question

I have a table

ID | Amount
-------------
1  | 500
2  | 800
3  | 200

How can I transfer 300 from second row to first row using their Id, I can do it by Stored Procedure, is there any way to perform this in single query

Answer 1

MySql evaluates Boolean expressions as 1 or 0, so this will work:

update tablename
set amount = amount + (id = 1) * 300 - (id = 2) * 300
where id in (1, 2);

Or:

update tablename
set amount = amount + ((id = 1) - (id = 2)) * 300
where id in (1, 2);

See the demo .
Results:

| ID  | Amount |
| --- | ------ |
| 1   | 800    |
| 2   | 500    |
| 3   | 200    |

Answer 2

You can try this:

UPDATE table_users
    SET amount = (case when id = 1 then amount+300
                         when id = 2 then amount-300
                    end)
    WHERE id in (1,2);