Sql: group by/ having

Question

Hi,
I have the follwoing table:
agt relationship startdate enddate
9000 83 1/23/04 2/23/34
9000 83 3/23/01 3/3/06
9000 83 7/4/08 5/5/05
9002 34 4/4/05 4/3/08
9002 23 4/4/05 2/2/06
9002 23 6/6/06 7/7/06
I would like to write a query which tells me if there is no record in a group of agt and relationships where enddate > SYSDATE and startdate <= sysdate.
In other words, there can be multiple records with the same agt and relationship, but I don't care how many records there are for each group (set of records with the same agt and relationship). All I need to know is if there is any group where sysdate doesn't fall between the startdate and enddate. For example, for the first 3 records described above (the first three records form a group since they have the same agt and relationship), the second and third records are past since sysdate is greater than the enddate. But because there is at least one record which is still active (the first record has an enddate in the future), I'm all set with that. But the third group (agt = 9002 and relationship = 23) has 2 records but both of them are past. I need to identify this group of records because it doesn't have any active dates.
Can anybody help?
Thanks!

Answer 1

You can also use:
SELECT agt, relationship, startdate, enddate
FROM (
select agt, relationship, startdate, enddate
, MAX(CASE WHEN SYSDATE BETWEEN startdate AND enddate THEN 'Y' ELSE 'N' END) OVER(PARTITION BY agt, relationship) valid
from t)
WHERE valid = 'N';
Sometimes there's a performance improvement if you can avoid a NOT IN condition and repeatedly accessing the same table (if it happens to be large in size).
The inner query determines if there exists at least one record in an (agt, relationship) group where SYSDATE BETWEEN startdate AND enddate. The outer query limits the result to only those groups where no such record exists.