How can I SELECT rows with MAX(Column value), DISTINCT by another column in SQL?

General Tech Bugs & Fixes 2 years ago

0 2 0 0 0 tuteeHUB earn credit +10 pts

5 Star Rating 1 Rating

Posted on 16 Aug 2022, this text provides information on Bugs & Fixes related to General Tech. Please note that while accuracy is prioritized, the data presented might not be entirely correct or up-to-date. This information is offered for general knowledge and informational purposes only, and should not be considered as a substitute for professional advice.

Take Quiz To Earn Credits!

Turn Your Knowledge into Earnings.

tuteehub_quiz

Answers (2)

Post Answer
profilepic.png
manpreet Tuteehub forum best answer Best Answer 2 years ago

 

My table is:

id  home  datetime     player   resource
---|-----|------------|--------|---------
1  | 10  | 04/03/2009 | john   | 399 
2  | 11  | 04/03/2009 | juliet | 244
5  | 12  | 04/03/2009 | borat  | 555
3  | 10  | 03/03/2009 | john   | 300
4  | 11  | 03/03/2009 | juliet | 200
6  | 12  | 03/03/2009 | borat  | 500
7  | 13  | 24/12/2008 | borat  | 600
8  | 13  | 01/01/2009 | borat  | 700

I need to select each distinct home holding the maximum value of datetime.

Result would be:

id  home  datetime     player   resource 
---|-----|------------|--------|---------
1  | 10  | 04/03/2009 | john   | 399
2  | 11  | 04/03/2009 | juliet | 244
5  | 12  | 04/03/2009 | borat  | 555
8  | 13  | 01/01/2009 | borat  | 700

I have tried:

-- 1 ..by the MySQL manual: 

SELECT DISTINCT
  home,
  id,
  datetime AS dt,
  player,
  resource
FROM topten t1
WHERE datetime = (SELECT
  MAX(t2.datetime)
FROM topten t2
GROUP BY home)
GROUP BY datetime
ORDER BY datetime DESC

Doesn't work. Result-set has 130 rows although database holds 187. Result includes some duplicates of home.

-- 2 ..join

SELECT
  s1.id,
  s1.home,
                                                
                                                
0 views
0 shares
profilepic.png
manpreet 2 years ago
-- Test data
DECLARE @TestTable TABLE (id INT, home INT, date DATETIME, 
  player VARCHAR(20), resource INT)
INSERT INTO @TestTable
SELECT 1, 10, '2009-03-04', 'john', 399 UNION
SELECT 2, 11, '2009-03-04', 'juliet', 244 UNION
SELECT 5, 12, '2009-03-04', 'borat', 555 UNION
SELECT 3, 10, '2009-03-03', 'john', 300 UNION
SELECT 4, 11, '2009-03-03', 'juliet', 200 UNION
SELECT 6, 12, '2009-03-03', 'borat', 500 UNION
SELECT 7, 13, '2008-12-24', 'borat', 600 UNION
SELECT 8, 13, '2009-01-01', 'borat', 700

-- Answer
SELECT id, home, date, player, resource 
FROM (SELECT id, home, date, player, resource, 
    RANK() OVER (PARTITION BY home ORDER BY date DESC) N
    FROM @TestTable
)M WHERE N = 1

-- and if you really want only home with max date
SELECT T.id, T.home, T.date, T.player, T.resource 
    FROM @TestTable T
INNER JOIN 
(   SELECT TI.id, TI.home, TI.date, 
        RANK() OVER (PARTITION BY TI.home ORDER BY TI.date) N
    FROM @TestTable TI
    WHERE TI.date IN (SELECT MAX(TM.date) FROM @TestTable TM)
)TJ

0 views   0 shares

No matter what stage you're at in your education or career, TuteeHub will help you reach the next level that you're aiming for. Simply,Choose a subject/topic and get started in self-paced practice sessions to improve your knowledge and scores.