Selecting most recent date between two columns

Question

If I have a table that (among other columns) has two DATETIME columns, how would I select the most recent date from those two columns.

Example:

Answer 1

You can throw this into a scalar function, which makes handling nulls a little easier. Obviously it isn't going to be any faster than the inline case statement.

ALTER FUNCTION [fnGetMaxDateTime] (
    @dtDate1        DATETIME,
    @dtDate2        DATETIME
) RETURNS DATETIME AS
BEGIN
    DECLARE @dtReturn DATETIME;

    -- If either are NULL, then return NULL as cannot be determined.
    IF (@dtDate1 IS NULL) OR (@dtDate2 IS NULL)
        SET @dtReturn = NULL;

    IF (@dtDate1 > @dtDate2)
        SET @dtReturn = @dtDate1;
    ELSE
        SET @dtReturn = @dtDate2;

    RETURN @dtReturn;
END