Question

I have table T1 and T2.

T1

ID    TIME1    TIME2  
1001    1        10
1002    1        20

T2

ID        STATUS    TIME
1001      NEW         1
1001      CLOSED      10
1002      NEW         1
1002      HOLD        5
1002      CLOSED      13

I want result TIME2-TIME1 if status HOLD does not exist in table T2; or TIME2-TIME1-TIME if status HOLD exist in table for that record

1001   9 (10-1)
1002   14(20-1-5)

I initially wrote SQL query but this does not work because it returns NULL for first record while the for the second record result is OK

SELECT T1.ID,T1.TIME2-T1.TIME1-T2.TIME
FROM T1
LEFT OUTER JOIN T2 ON T1.ID=T2.ID AND T2.STATUS='HOLD'

Thanks

Answer 1

or in short

select 
    t1.id,
    t1.time2-case when status='HOLD' then t2.time else 0 end-t1.time1
from
    t1 left join t2 on t1.id=t2.id and t2.status='HOLD'