Tell SQL Server the error is "handled" in try...catch - sql-server-2005

Question

I'd like to indicate to SQL Server 2005, in my BEGIN CATCH...END CATCH block that the error is "handled"... That is, clear the error.
Is that possible? Consider this:
begin transaction
begin try
begin transaction
select cast('X' as bit)
commit transaction
end try
begin catch rollback transaction
select error_number(), error_message()
end catch
commit transaction
This results in the following:
(0 row(s) affected)
(No column name) (No column name)
245 Conversion failed when converting the varchar value 'X' to data type bit.
(1 row(s) affected)
Msg 3902, Level 16, State 1, Line 13
The COMMIT TRANSACTION request has no corresponding BEGIN TRANSACTION.
Thanks.
A.

Answer 1

Not all errors are maskable. You are always supposed to inspect the XACT_STATE() and see if you can continue. Certain errors (1205 deadlock being a typical example) will rollback the transaction and not allow you to continue.
What you describe (a loop which can preserve the work) is ussualy done with the help of a savepoint:
begin transaction
begin try
while #loopcondition
begin
save transaction loop;
begin try
-- process loop element here
end try
begin catch
if xact_state() = -1
begin
-- whole transaction is doomed
rollback;
raiserror ('Aborting', ....);
end
else if xact_state() = 0
begin
-- trasaction was aborted by inner loop
raiserror ('Aborted inside', ....);
end
else if xact_state() = 1
begin
-- this error is recoverable, rollback to the savepoint and continue the loop
rollback loop
end
end catch
-- continue loop here
fetch next from ....
/*
-- batch commit here if batch committing
if #batchsize
begin
commit;
begin transaction
end
*/
end
commit;
end try
begin catch
-- if we get here, we could not handle the error inside the loop and continue
if xact_state() != 0
rollback
raiserror('failed to process', ...)
end catch