No, It is not recommended to do that as it kills the 
performance.

Best option will be to select the data before loop and 
inside loop use read statement.

select f1 f2 f3(key fields) from db into 
                iNtertab
                for all entries in itab
                       where condition.
sort intertab by f1.
loop at itab.
read intertab with key f1 = itab-f1
                   binary search.
Endloop.