Sort by minimum value of two columns

Question

I use SQL Server 2008 R2.

I need to sort a table by the minimal value of two columns.

The table looks like this:

ID: integer; 
Date         


        

Answer 1

The simplest way is using of the VALUES keyword, like the following:

SELECT ID, Date1, Date2
FROM YourTable
ORDER BY (SELECT MIN(v) FROM (VALUES (Date1), (Date2)) AS value(v))

This code will work for all the cases, even with nullable columns.

Edit :

The solution with the COALESCE keyword is not universal. It has the important restrictions:

• It won't work if the columns are of the Date type (if you use the dates before 01/01/1753)
• It won't work in case one of the columns is NULL. It interprets the NULL value as the minimal datetime value. But is it actually true? It isn't even datetime, it is nothing.
• The IF expression will be much more complicated if we use more than two columns.

According to the question:

What is the simplest way to sort this table that way?

The shortest and the simplest solution is the one which described above, because:

• It doesn't take a lot of coding to implement it - simply add an one more line.
• You don't need to care about whether the columns are nullable or not. You just use the code and it works.
• You can extend the number of columns in your query simply by adding the one after a comma.
• It works with the Date columns and you don't need to modify the code.

Edit 2 :

Zohar Peled suggested the following way of order:

I would order the rows by this rules: first, when both null, second, when date1 is null, third, when date 2 is null, fourth, min(date1, date2)

So, for this case the solution can be reached by using of the same approach, like the following:

SELECT ID, Date1, Date2
FROM YourTable
ORDER BY 
CASE WHEN Date1 IS NULL AND Date2 IS NULL THEN 0
     WHEN Date1 IS NULL THEN 1
     WHEN Date2 IS NULL THEN 2
     ELSE 3 END,
(SELECT MIN(v) FROM (VALUES ([Date1]), ([Date2])) AS value(v))

The output for this code is below:

The COALESCE solution will not sort the table this way. It messes up the rows where at least one cell of the NULL value. The output of it is the following:

Hope this helps and waiting for critics.