MySQL NOT IN查詢給出錯誤結果

Question

select count(*) from call_log
where relation_id in (14,15)
and date(from_unixtime(created_time/1000)) = '2018-12-10';

結果：1600

select count(*) from call_log
where relation_id in (14,15)
and date(from_unixtime(created_time/1000)) = '2018-12-10'
and id not in (NULL);

結果：0

select count(*) from call_log
where relation_id in (14,15)
and date(from_unixtime(created_time/1000)) = '2018-12-10'
and id in (NULL);

結果：0

理想情況下，查詢2和3的結果總和應等於查詢1的結果。或者與NULL比較時存在一些問題。

Answer 1

IN()無法處理NULL值。 改為使用IS

and id is not NULL

要么

and id is NULL