Problem with null value query for Mysql not in

One problem that is found today in MySQL's not-in use is roughly:

Select *  from where  not inch (Select from B).

found that the query results are 0 records anyway. Later found that the query result set returned in B has a null value, looked up the data only to know that MySQL does not inside if there is a null value, will return 0 records.

To solve this problem, you need to turn select FID from B into

Select  from where  is  not NULL

This is also the problem in other databases, because the processing of not is problematic. Further details, as follows:

Select *  from where  not inch (1,2,null )

Then there is no record return, because there is a null value, when compared with the ID and NULL, it will return false, so a record will not return, so you have to change to the following:

Select *  from where  not inch (Selectfromwhere bid   is  not NULL

Problem with null value query for Mysql not in