IIF function is used to do logical operation equivalent to IF...ELSE statement.
SELECT IIF ( -1 < 1, 'TRUE', 'FALSE' ) AS Result;
OutPut
Result
-------
TRUE
IIF function is only available in
MSSQL 2012. To do this kind of operation in MSSQL 2008, we can simulate the above operation by using CASE...WHEN statement in single SELECT or IF..ELSE in T-SQL code
SELECT CASE
WHEN -1 < 1 THEN 'TRUE'
ELSE 'FALSE' END AS Result;
OutPut
Result
-------
TRUE
Sample for IIF usage in Queries: Displaying Gender M as Male; F as Female
DECLARE @details TABLE(name VARCHAR(50), Gender CHAR(1))
INSERT @details VALUES('Chandu','M'),('Deepa','F'),('Sukesh','M'),('Aruna','F'),('Mohana','F'),('Arun',NULL)
SELECT name,IIF(Gender = 'M', 'Male','Female') AS 'Gender' FROM @details