Use an index on both tables (usually primary key) (loan in example)

open both tables

Select 1
use ...
set order to loan &&&(tag built as index on loanaccount tag loan)

Select 2
use ...
set order to loan

select table1
go top

do while (.not.eof())
select table2
seek table1.loanaccount

If len(alltrim(table2.comparefield)) = 0 &&& empty (or use = 0 for numeric)
replace table2.comparefield with table1.comparefield
endif

select table1
skip

enddo

- Kev