Get the minimum value between several columns

Question

I\'m using SQL Server 2008;

Suppose I have a table \'X\' with columns \'Date1\', \'Date2\', \'Dateblah\', all of type DateTime.

I want to select the min valu

Answer 1

Implementing a scalar function:

CREATE FUNCTION [dbo].[MIN](@a SQL_VARIANT, @b SQL_VARIANT)
RETURNS SQL_VARIANT
AS 
BEGIN
    RETURN (
        SELECT MIN([x])
        FROM (VALUES(@a),(@b)) x([x])
    )   
END
GO

DECLARE @a DATETIME = '12 JUL 2011', @b DATETIME = '20 AUG 2011'
SELECT [dbo].[MIN](@a, @b)

DECLARE @c INT = 12, @d INT = 32
SELECT [dbo].[MIN](@c, @d)