Question

My problem is this:
I need to select values from “groups” table that do not contain specific “user_id”.
So I execute this:

SELECT DISTINCT group.active, hide_group.user_id, group.group_id, hide_group.hide, group.desc AS group_desc
FROM group
LEFT JOIN hide_group ON hide_group.group_id = group.group_id
WHERE (
hide_group.user_id != 'testuser'
OR hide_group.user_id IS NULL
AND (
hide != 'true'
OR hide IS NULL
)
)
AND active =1
ORDER BY `group`.`group_id` ASC
LIMIT 0 , 500 

But now lets say we have such records in my ‘group_hide’ table:

[group_hide]
(user_id, group_id, hide)
john, ABC, true;
joe, ZZZ, true;
mark, ABC, true;

So now when I do my query, mark still sees ABC group, because the condition is true and valid because user_id = john and we therefor take the ABC value, even when it is hidden for mark.
I have tried changing this query several times, but I can’t figure out this simple problem.

Answer 1

I suggest using a subquery:

SELECT *
FROM group
WHERE group_id NOT IN (
    SELECT group_id
    FROM group_hide
    WHERE user_id = 'testuser'
    AND hide = true)
AND active =1
ORDER BY `group`.`group_id` ASC
LIMIT 0 , 500