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

I would order the rows by this rules:

1. when both null
2. when date1 is null
3. when date 2 is null
4. min(date1, date2)

To do this a nested case will be simple and efficient (unless the table is very large) according to this post.

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,
CASE 
  WHEN Date1 < Date2 THEN Date1
  ELSE Date2
END