c# - SQL Server: Rethrow exception with the original exception number

Question

I am using a TRY CATCH block in a stored procedure where I have two INSERT instructions.

If something goes wrong, the CATCH block takes care of rolling back all changes made and it works fine, except one thing!

The exception caught by my ASP.NET application is a SqlException with number 50000. This is not the original number! (the number I was expecting was a 2627)

In the Message property of the exception I can see the original exception number and message formated.

How can I get the original exception number?

try
{
    // ... code
}
catch
(SqlException sqlException)
{
    switch (sqlException.Number)
    {
        // Name already exists
        case 2627:
            throw new ItemTypeNameAlreadyExistsException();

        // Some other error
        // As the exception number is 50000 it always ends here!!!!!!
        default:
            throw new ItemTypeException();
    }
}

Right now the return value is already being used. I guess that I could use an output parameter to get the exception number, but is that a good idea?

What can I do to get the exception number? Thanks

PS: This is needed because I have two INSERT instructions.

Answer 1

You might be able to rethrow it like this:

..
END TRY
BEGIN CATCH
    DECLARE @errnum int;
    SELECT @errnum = ERROR_NUMBER();
    RAISERROR (@errnum, 16, 1);
END CATCH

However, you most likely lose a lost of meaning because of the %s etc placeholders in the sys.messages rows for ERROR_NUMBER()

You could do something like this to include the number and rethrow the original message

..
END TRY
BEGIN CATCH
    DECLARE @errnum nchar(5), @errmsg nvarchar(2048);
    SELECT
        @errnum = RIGHT('00000' + ERROR_NUMBER(), 5),
        @errmsg = @errnum + ' ' + ERROR_MESSAGE();
    RAISERROR (@errmsg, 16, 1);
END CATCH

The first 5 chars are the original number.

But if you have nested code, then you'll end up with "00123 00456 Error text".

Personally, I only deal with SQL Exception numbers to separate my errors (50000) from Engine errors (eg missing parameters) where my code does not run.

Finally, you could pass it out the return value.

I asked a question on this: SQL Server error handling: exceptions and the database-client contract