mysql - 获取表的ID并存储在变量中

Question

我想将最后更新的行的id存储到一个变量中，然后设置一个触发器来更新一些单元格，触发器的代码:

BEGIN
DECLARE MYROW_ID INT;
DECLARE WITHDRAWAL DECIMAL(11,1);
DECLARE USERNAME VARCHAR(10);
SET MYROW_ID = SELECT id FROM withdrawals ORDER BY lastmodified DESC LIMIT 1;
SET WITHDRAWAL = SELECT withdrawal FROM withdrawals WHERE id = MYROW_ID;
SET USERNAME = SELECT username FROM withdrawals WHERE id = MYROW_ID;
UPDATE  `interests` SET  `totalincome` =  `totalincome` - 'WITHDRAWAL'
WHERE 'username' = 'USERNAME' AND 'status' = 1;
END

MySQL 在第 5 行给出了错误，我是否分配了错误的数据类型，即 MYROW_ID？
如何将 SELECT 返回的值存储到 MYROW_ID 中？

Answer 1

你应该这样做:

SELECT id into MYROW_ID FROM withdrawals ORDER BY lastmodified DESC LIMIT 1;