Performance issue. LIKE in WHERE CLAUSE

Hi Experts,

I have a performance issue. My scenario is,

There is an internal table in the prg with invoice number : 1900000001

In other table, i have another field which have value as inv number + fiscal year as

19000000012009.

In order to fetch only matching entries, i am looping on the first int tab and add the inv+ fisc year into

another int table and later making select with for all entries as

loop at itab into wa.

concatenate inv + fisc year

append to itab2.

endloop.

select *

from b

into table --

for all entries in itab2

where field = itab2-field

Is there any way i can skip the loop and can directly select, either by using LIKE or any other statement

2) If i want to proceed in other way round.

first select from b into itab,

loop at itab into wa.

move field0(10) to wa2

append wa2 to itab2.

endloop.

Can i skip the loop in this case.

Thanks,