MySQL NOT IN查询给出错误结果

Question

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

结果：1​​600

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);

结果：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);

结果：0

理想情况下，查询2和3的结果总和应等于查询1的结果。或者与NULL比较时存在一些问题。

Answer 1

IN()无法处理NULL的值。而是使用IS

and id is not NULL

或

and id is NULL