SQL Server INLINE IF ELSE

--SQL SERVER INLINE IF ELSE.

--OLD DATABASE QUERY.
SELECT (CASE Flag WHEN 1 THEN 'Yes' ELSE 'No' END) AS if_else_Result

--NEW DATABASE QUERY.
SELECT IIF(1 = 1, 'Yes', 'No') AS if_else_Result;
SELECT IIF(1 = 2, 'Yes', 'No') AS if_else_Result;

SELECT IIF('a' = 'a', 'Yes', 'No') AS if_else_Result;
SELECT IIF('a' = 'b', 'Yes', 'No') AS if_else_Result;

The Result looks like,