I've got a table of data...

Loan number, tran code, acct, amt.

I need to sum the amounts for the loan number that equal a certain tran code
and acct number. For example, sum acct #11900 for tran codes 88 and 6 for a
certain loan number. The table has several transactions for one loan number.

Can someone help?? My problem is looking up the loan number before summing
the information I need.