如果值不存在,查找记录？

Question

我遇到SQL查询问题.

我想StatusID = 1在records表中找到IF StatusID = 2不存在.

我试过了这个问题:

SELECT * FROM records AS A
   LEFT JOIN records AS B on B.StoreID = A.StoreID
WHERE A.StatusID = 1 AND B.StatusID != 2

即使StatusID = 2存在,它仍然显示结果.

注意:StoreID是记录表中的ref id.

Answer 1

你想用NOT EXISTS:

SELECT * 
FROM records AS A
WHERE A.StatusID = 1 
AND NOT EXISTS (select B.StoreID 
                from records AS B 
                where B.StoreID = A.StoreIDB 
                and B.StatusID = 2)