How do I select the first row per group in an SQL Query?

Question

I\'ve got this SQL query:

SELECT   Foo, Bar, SUM(Values) AS Sum
FROM     SomeTable
GROUP BY Foo, Bar
ORDER BY Foo DESC, Sum DESC

This resul

Answer 1

It's an old post but I had the same problem today. I've solved it by trying many queries until it works. I'm using SQL Compact 3.5 with visual basic 2010.

This example is for a table named "TESTMAX" with columns "Id" (primary key), "nom" (name) and "value", you can use this to obtain rows with max "value" for each "nom" :

SELECT TESTMAX.Id, TESTMAX.NOM, TESTMAX.Value
FROM     TESTMAX INNER JOIN
                  TESTMAX AS TESTMAX_1 ON TESTMAX.NOM = TESTMAX_1.NOM
WHERE  (TESTMAX.Value IN
                      (SELECT MAX(Value) AS Expr1
                       FROM      TESTMAX AS TESTMAX_2
                       WHERE   (NOM = TESTMAX_1.NOM)))
GROUP BY TESTMAX.Id, TESTMAX.NOM, TESTMAX.Value

If you want to delete the other rows, you can also use :

DELETE FROM TESTMAX
WHERE  (Id NOT IN
                      (SELECT TESTMAX_3.Id
                       FROM      TESTMAX AS TESTMAX_3 INNER JOIN
                                         TESTMAX AS TESTMAX_1 ON TESTMAX_3.NOM = TESTMAX_1.NOM
                       WHERE   (TESTMAX_3.Value IN
                                             (SELECT MAX(Value) AS Expr1
                                              FROM      TESTMAX AS TESTMAX_2
                                              WHERE   (NOM = TESTMAX_1.NOM)))
                       GROUP BY TESTMAX_3.Id, TESTMAX_3.NOM, TESTMAX_3.Value))