SELECT only latest record of an ID from given rows

Question

I have this table shown below...How do I select only the latest data of the id based on changeno?

+----+--------------+------------+--------+
| id |  data   | ch         


        

Answer 1

This is typically referred to as the "greatest-n-per-group" problem. One way to solve this in SQL Server 2005 and higher is to use a CTE with a calculated ROW_NUMBER() based on the grouping of the id column, and sorting those by largest changeno first:

;WITH cte AS 
(
  SELECT id, data, changeno,
    rn = ROW_NUMBER() OVER (PARTITION BY id ORDER BY changeno DESC)
  FROM dbo.Table1
)
SELECT id, data, changeno
  FROM cte
  WHERE rn = 1
  ORDER BY id;