Calculate the New KF (Actual work) based on finsh date and selection date

Hi Friends,

I have a requirement to calculate the new KF actual work based on the finish date and start date .

I have  all fields in Bex query :

ISMNW - Actual work    -  KF

IEDD    - Finish date     - Ch

Start date as   Variable on 0CALDAY.

Now :  Logic is :  ADD all ISMNW  where IEDD is less then or equal to Start date.

Thanks,