How to use maximum date condition in where clause ?

Question

Hi I want to check if SWITCH_FLAG has 'Y' for the latest batch run..how can write it?
(select a.SWITCH_FLAG
from MORTGAGE
where SYS_EFF_DATE = max(SYS_EFF_DATE)
) as expected_result
Error message:
ORA-00934: group function is not allowed here

Answer 1

This will give you the switch_flag for the latest eff_date,
SELECT SWITCH_FLAG
  FROM (SELECT A.SWITCH_FLAG, ROW_NUMBER () OVER (ORDER BY SYS_EFF_DATE DESC) rn
          FROM mortgage A)
WHERE rn = 1;
--if you want to test try this,
SELECT SWITCH_FLAG,SYS_EFF_DATE
  FROM (SELECT A.SWITCH_FLAG,SYS_EFF_DATE , ROW_NUMBER () OVER (ORDER BY SYS_EFF_DATE DESC) rn
          FROM mortgage A)
WHERE rn = 1;G.