* Henning Sprang
> Now I want to create a query to get all task_id's which one given User
> isn't already assigned to. I tried a lot of things, Joined in every
> direction and so but do not come to my result.
The problem in this situation is that you want to join with records that are
not there. I suppose you have no problem selecting the Tasks that _are_
assigned to a User.
To find the non-existing records, you need to use LEFT JOIN. You use it like
a normal JOIN, but a LEFT JOIN returns a row even if the associated record
is not found, and fills all fields from that record with NULL. Because the
non-existing records are what you want in this case, you add a
ISNULL(Auth.user_id) to your WHERE clause:
SELECT Task.task_id
FROM Task,User
LEFT JOIN Auth ON
Auth.user_id=User.user_id AND
Auth.task_id=Task.task_id
WHERE
ISNULL(Auth.user_id) AND
User.username="roger";
--
Roger
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