find rows that don't match

[wouter0809]

I've got two tables: item an trial
The answer to the items is saved in table trial.
I want to select those items that haven't been made in the current session.
The answer to the items is saved in table trial.

I used:

select item.item_id, trial.test.session_id
from item left join trial
using(item_id)
where trial.item_id is null

this selects the items that havent been made yet.

It should retrieve all items in a new session
But retrieves only those that haven't been made in the old session.

how can I add an extra line that like:

and trial.session_id=&quot;<current_session>&quot;

select item.item_id, trial.test.session_id
from item left join trial
using(item_id)
where trial.item_id is null
and trial.session_id=&quot;<current_session>&quot;

this returns: there is no data macthving your request.

can somebody help me out??

thanx

Wouter Pasman

 

[nigelcohen]

Wouter

I tried the following with a similar issue, which worked:

select a.Ref, b.Ref
from ATable a left outer join BTable b
on a.Ref = b.Ref
where a.Ref is null


(If I had tried b.Ref, the response would have been a failure because there would have been no null records. In this case, I would have either switched the order of the tables in the &quot;from&quot; statement, or replaced &quot;left outer&quot; with &quot;right outer&quot;.)

I hope this fixes your problem