You can remove leading zeros using PATINDEX, LEFT and RIGHT. The ISNULL and NULLIF are to handle the case when all digits are zero. CASE WHEN LEFT(Data, 1) = '0' THEN RIGHT(Data, LEN(Data) - ISNULL(NULLIF(PATINDEX('%[^0]%', Data), 0), LE...

Here's another way to sum the digits of a 32-bit signed integer. CREATE FUNCTION SumOfDigits(@N int) RETURNS int AS BEGIN RETURN ( SELECT ABS(@N) % 10 + ABS(@N) / CAST(1E1 AS int) % 10 + ABS(@N) / CAST(1E2 AS ...