T-SQL Scalar Function Returning NULL for Non-NULL Input in SQL Server 2016
I'm working with an scenario with a scalar function in T-SQL that is supposed to return a calculated value based on input parameters. However, when I pass a non-NULL value to the function, it unexpectedly returns NULL instead. Here's the function definition: ```sql CREATE FUNCTION dbo.CalculateDiscount(@Price DECIMAL(10, 2)) RETURNS DECIMAL(10, 2) AS BEGIN IF @Price <= 0 RETURN NULL; RETURN @Price * 0.1; END ``` I tested this function with the following query: ```sql SELECT dbo.CalculateDiscount(150) AS Discount; ``` I expected the output to be `15.00`, but instead, it returns `NULL`. I've double-checked the input value, and it is definitely greater than zero. I've also tested the function with various inputs (100, 250, etc.), but it consistently returns NULL. After a bit of debugging, I noticed that the function seems to work properly when called directly in a simple query but fails when incorporated into a larger query: ```sql SELECT ID, dbo.CalculateDiscount(Price) AS Discount FROM Products; ``` In this case, for some rows, it returns NULL for valid prices. The `Products` table has a structure like this: ```sql CREATE TABLE Products ( ID INT PRIMARY KEY, Price DECIMAL(10, 2) ); ``` Could there be a data type scenario or a question with how I'm using the function in a query context? Any insights would be greatly appreciated!