SQL Scalar-Valued Function - sql-server

Question

I am looking to retrieve a value of the profit (FilmBoxOfficeDollar - FilmBudgetDollars) based on the Studio given as a parameter to the function.
USE Movies;
GO
CREATE FUNCTION fnmovieProfits(#StudioName nvarchar(255))
RETURNS int
AS
BEGIN
RETURN (SELECT SUM(FilmBoxOfficeDollars - FilmBudgetDollars)
FROM Film JOIN Studio
ON Film.FilmStudioID = Studio.StudioID
WHERE StudioName = #StudioName);
END;
GO
SELECT [dbo].[fnmovieProfits]('Dreamworks');
Whenever I run this through to pull the piece of data I get the following error:
Msg 8115, Level 16, State 2, Line 13
Arithmetic overflow error converting expression to data type int.
Any help would be much appreciated!

Answer 1

The problem you are experiencing is that you are overflowing the allowed value of a 32 bit number (INT); if you cast/convert to a 64 bit number (BIGINT) and return that datatype, the issue will be corrected. Proof of concept showing the issue:
DECLARE #BigNumber INT=2000000000
select CONVERT(BIGINT,#BigNumber) + CONVERT(BIGINT,#BigNumber) --returns 4,000,000,000
select (#BigNumber + #BigNumber) --errors with "Arithmetic overflow error converting expression to data type int."
BUT, do yourself a favor and use a view instead. Scalars like that are terrible for performance in reports. Scalar functions should never be used unless they are simply doing calculations based on input values (i.e. not hitting underlying, persisted data).
CREATE VIEW dbo.v_StudioProfits
AS
SELECT
StudioName,
SUM(CONVERT(BIGINT,FilmBoxOfficeDollars) - CONVERT(BIGINT,FilmBudgetDollars)) AS [Profit]
FROM Film
INNER JOIN Studio ON Film.FilmStudioID = Studio.StudioID
GROUP BY StudioName
GO
SELECT * FROM dbo.v_StudioProfits WHERE StudioName='Dreamworks'
Relevant reading on SQL Server datatypes. Specifically, integer datatypes.

Answer 2

Your sum is exceeding int range. You should define your return type as bigint:
CREATE FUNCTION fnmovieProfits(#StudioName nvarchar(255))
RETURNS bigint
AS.......
The maximum value you can return with int as a return type is 2147483647. Your sum is probably bigger than that.
One example of function that exceeds its return type:
CREATE FUNCTION testFunction()
RETURNS int
AS
BEGIN
RETURN (SELECT 2147483647 + 1);
END;
GO
SELECT [dbo].[testFunction]();
If you execute it you will get the following error:
Msg 8115, Level 16, State 2, Line 8
Arithmetic overflow error converting expression to data type int.
So the solution is just to increase your return type range by replacing int with bigint.