How to Find Missing Value Between Two Mysql Tables

select userid from cw_users where NOT EXISTS(Select userid from cw_users_data)

The previous query won't do the job of course.

Trying to find only a missing 'userid' from tableb by doing a comparison.

Both tables contain 'userid' and there should be one similar on each. I'm trying to find which one is missing on second table.开发者_开发知识库

Another method

SELECT cw_users.userid FROM cw_users
LEFT JOIN cw_users_data ON cw_users.userid=cw_users_data.userid
WHERE cw_users_data.userid IS NULL;

select userid from cw_users where userid not in(select userid from cw_users_data)

how about this

select userid from cw_users where userid not in (Select userid from cw_users_data)

Try this

Select  userid from cw_users 
Except
Select userid from cw_users_data