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;

Answer 2

for other alternatives :

DECLARE @Table1 TABLE
(
 id INT, data VARCHAR(5), changeno INT
);

INSERT INTO @Table1
SELECT 1,'Yes',1
UNION ALL
SELECT 2,'Yes',2
UNION ALL
SELECT 2,'Maybe',3
UNION ALL
SELECT 3,'Yes',4
UNION ALL
SELECT 3,'Yes',5
UNION ALL
SELECT 3,'No',6
UNION ALL
SELECT 4,'No',7
UNION ALL
SELECT 5,'Maybe',8
UNION ALL
SELECT 5,'Yes',9

SELECT Y.id, Y.data, Y.changeno
FROM @Table1 Y
INNER JOIN (
    SELECT id, changeno = MAX(changeno) 
    FROM @Table1 
    GROUP BY id
) X ON X.id = Y.id 
WHERE X.changeno = Y.changeno
ORDER BY Y.id

Answer 3

You want to use row_number() for this:

select id, data, changeno
from (SELECT t.*,
             row_number() over (partition by id order by changeno desc) as seqnum
      FROM Table1 t
     ) t
where seqnum = 1;

Answer 4

Not a well formed or performance optimized query but for small tasks it works fine.

SELECT * FROM TEST WHERE changeno IN (SELECT MAX(changeno) FROM TEST GROUP BY id)