.net - SQL NOT IN 子句

Question

我有一个查询没有按预期工作

Q1:
SELECT id, name 
FROM vw_x 
WHERE id NOT IN (select pid from table_x)
GROUP BY id, name
Having max(c_date) > GETDATE()

Q2:
SELECT id, name 
FROM vw_x 
GROUP BY id, name
Having max(c_date) > GETDATE()

即使我知道这些 ID 不在 table_x 中，Q1 也没有返回任何内容
Q2 在没有 NOT IN 的情况下正确运行

我的查询可能有什么问题？

Answer 1

你在表中有一个 NULL 值

尝试这个

SELECT id, name 
FROM vw_x 
WHERE id NOT IN (select pid from table_x where pid is not null)
GROUP BY id, name
Having max(c_date) > GETDATE()

或这个

SELECT id, name 
FROM vw_x 
WHERE  NOT EXISTS (select 1 from table_x  where pid = vw_x.id  )
GROUP BY id, name
Having max(c_date) > GETDATE()

另见 Select all rows from one table that don't exist in another table