MS sql 2008 try catch still throws exception - sql

Question

I worried all day.
My label is very big - '20317302009001'.
Zlecenie is int column - so sql generates error when compare zlecenie=#label.
I tried to catch it, but still get message:
Msg 248, Level 16, State 1, Procedure label_check, Line 9
The conversion of the varchar value '20317302009001' overflowed an int column.
Who knows the answer?
Thank you!
begin TRY
if (#komponent is null) and ISNUMERIC(#label)=1
begin
set #komponent=null
if exists(select * from Rejestr_zuzycia_tkaniny where zlecenie=#label)
begin
declare #program int;
select #program=program from Rejestr_zuzycia_tkaniny where zlecenie=#label
select #komponent=komponent from Komponenty_programu where program=#program
end;
end;
end TRY
begin CATCH
set #komponent=null
end CATCH

Answer 1

From your code, it looks like you don't actually use zlecenie as a number, so you might want to compare by casting it as a varchar first like so:
if exists(select * from Rejestr_zuzycia_tkaniny where cast(zlecenie as varchar(20))=#label)
However, if you do need to process zlecenie as a number later on e.g. add it to something, then you might want to make it a bigint instead of int to accommodate large values.
MSDN has this to say about TRY...CATCH in T-SQL:
The following types of errors are not handled by a CATCH block when they occur at the same level of execution as the TRY…CATCH construct:
Compile errors, such as syntax errors, that prevent a batch from running.
Errors that occur during statement-level recompilation, such as object name resolution errors that occur after compilation because of deferred name resolution.
I believe that the arithmetic overflow error might belong to the second scenario, which would explain why the CATCH block does not handle it. However, I have not been able to get any corroboration elsewhere so I suggest you do not just take my word for it.