SQL: Return “true” if list of records exists?

Question

An alternative title might be: Check for existence of multiple rows?

Using a combination of SQL and C# I want a method to return true if all products in a list exist

Answer 1

I know this is old but I think this will help anyone else who comes looking...

SELECT CAST(COUNT(ProductID) AS bit) AS [EXISTS] FROM Products WHERE(ProductID = @ProductID)

This will ALWAYS return TRUE if exists and FALSE if it doesn't (as opposed to no row).