update problem

[Srivats Chandrasekaran]

1. If i want to do

if exists( select .... where ... ) then
update...
else
insert...

or

update...
if ( row_count() < 1) then
insert..

which causes lesser overhead, since in the first thing i am executing one extra query while checking.
There may be some cases where the where clause of the update satisfies but the values i am inserting will be the same in that case row_count() = 0 instead of 1. In this case the latter method will fail. Is there neway i can get the rows matched by the where clause of update statement.