Question

我有两张桌子，CHEF和MEAL。我想做的是减少每个尚未做过一顿饭的厨师的工资。这是我的查询

UPDATE CHEF
SET Chef_salary = Chef_salary-(Chef_salary/100 * 5)
WHERE Chef_ID=(SELECT c.Chef_ID
FROM CHEF c LEFT JOIN MEAL m ON (c.Chef_ID=m.Chef_ID)
HAVING count(m.Chef_ID)='0'
GROUP BY c.Chef_ID);;

它返回一个错误，表示“单行子查询返回多行” 我做错了什么？

Answer 1

UPDATE CHEF
SET Chef_salary = Chef_salary-(Chef_salary/100 * 5)
WHERE Chef_ID in (SELECT c.Chef_ID
FROM CHEF c LEFT JOIN MEAL m ON (c.Chef_ID=m.Chef_ID)
GROUP BY c.Chef_ID
HAVING count(m.Chef_ID)='0'
);

Answer 2

如果我理解你的逻辑，你需要NOT EXISTS和相关的子查询：

UPDATE CHEF
     SET Chef_salary = Chef_salary - (Chef_salary/100 * 5)
     WHERE NOT EXISTS (SELECT 1
                       FROM MEAL m
                       WHERE chef.Chef_ID = m.Chef_ID
                      );

Answer 3

Update CHEF c Set Chef_salary = Chef_salary-(Chef_salary/100 * 5)
Where c.Chef_ID not in (Select Chef_ID from MEAL m)

SQL两个表单行子查询返回多行

3 个答案: