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

There is no built in function to return the min/max of two (or more) columns. You could implement your own scalar function to do this.

In SQL Server 2005+ you could use UNPIVOT to turn the columns into rows and then use the MIN function:

CREATE TABLE [X]
(
    [ID] INT,
    [Date1] DATETIME,
    [Date2] DATETIME,
    [Date3] DATETIME
)

INSERT  [X]
VALUES  (0, '09/29/2011', '09/20/2011', '09/01/2011'),
        (1, '01/01/2011', '01/05/2011', '03/03/2010')


SELECT [ID], MIN([Date]) AS [MinDate]
FROM [X]
UNPIVOT (
    [Date] FOR d IN
        ([Date1]
        ,[Date2]
        ,[Date3])
) unpvt
GROUP BY [ID]