Bits of .NET

Scalar UDFs run row-by-row → slowest possible execution.

✔ Replace with Inline Table-Valued Function

CREATE FUNCTION GetPrice(@id INT)
RETURNS TABLE
AS
RETURN SELECT Price FROM Products WHERE Id = @id;

Then:

SELECT p.*, f.Price
FROM Orders o
CROSS APPLY GetPrice(o.ProductId) f;

💡 Boost

CPU ↓, IO ↓, query ↑.