How can I SELECT rows with MAX Column value DISTINCT by another column in SQL

Question

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    s1 datetime    s1 player    s1 resource FROM topten s1 JOIN  SELECT   id    MAX datetime  AS dt FROM topten GROUP BY id  AS s2   ON s1 id   s2 id ORDER BY datetime    Nope  Gives all the records   -- 3   something exotic     With various results

User · Answer

Why not using  SELECT home  MAX datetime  AS MaxDateTime player resource FROM topten GROUP BY home Did I miss something

User · Answer

Try this  select   from mytable a join  select home  max datetime  datetime from mytable group by home  b  on a home   b home and a datetime   b datetime   Regards K

User · Answer

Here goes T-SQL version   -- 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 ON TJ N   1 AND T id   TJ id   EDIT Unfortunately  there are no RANK   OVER function in MySQL  But it can be emulated  see Emulating Analytic  AKA Ranking  Functions with MySQL  So this is MySQL version   SELECT id  home  date  player  resource  FROM TestTable AS t1  WHERE       SELECT COUNT                 FROM TestTable AS t2              WHERE t2 home   t1 home AND t2 date  gt  t1 date         0

User · Answer

Try this for SQL Server   WITH cte AS      SELECT home  MAX year  AS year FROM Table1 GROUP BY home   SELECT   FROM Table1 a INNER JOIN cte ON a home   cte home AND a year   cte year

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this is the query you need    SELECT b id  a home b  datetime  b player a resource FROM   SELECT home MAX resource  AS resource FROM tbl 1 GROUP BY home  AS a   LEFT JOIN    SELECT id home  datetime  player resource FROM tbl 1  AS b  ON  a resource   b resource WHERE a home  b home

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Hope below query will give the desired output   Select id  home datetime player resource  row number   over  Partition by home ORDER by datetime desc  as rownum from tablename where rownum 1

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SELECT c1  c2  c3  c4  c5 FROM table1 WHERE c3    select max c3  from table   SELECT   FROM table1 WHERE c3    select max c3  from table1

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You are so close   All you need to do is select BOTH the home and its max date time  then join back to the topten table on BOTH fields   SELECT tt   FROM topten tt INNER JOIN      SELECT home  MAX datetime  AS MaxDateTime     FROM topten     GROUP BY home  groupedtt  ON tt home   groupedtt home  AND tt datetime   groupedtt MaxDateTime

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Another way to gt the most recent row per group using a sub query which basically calculates a rank for each row per group and then filter out your most recent rows as with rank   1  select a   from topten a where     select count      from topten b   where a home   b home   and a  datetime   lt  b  datetime     1   1   DEMO  Here is the visual demo for rank no for each row for better understanding      By reading some comments what about if there are two rows which have same  home  and  datetime  field values    Above query will fail and will return more than 1 rows for above situation  To cover up this situation there will be a need of another criteria parameter column to decide which row should be taken which falls in above situation  By viewing sample data set i assume there is a primary key column id which should be set to auto increment  So we can use this column to pick the most recent row by tweaking same query with the help of CASE statement like  select a   from topten a where     select count      from topten b   where a home   b home   and  case         when a  datetime    b  datetime         then a id  lt  b id        else a  datetime   lt  b  datetime         end     1   1   DEMO  Above query will pick the row with highest id among the same datetime values   visual demo for rank no for each row

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I think this will give you the desired result   SELECT   home  MAX datetime  FROM     my table GROUP BY home   BUT if you need other columns as well  just make a join with the original table  check Michael La Voie answer   Best regards

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This will work even if you have two or more rows for each home with equal DATETIME s   SELECT id  home  datetime  player  resource FROM            SELECT                 SELECT  id               FROM    topten ti               WHERE   ti home   t1 home               ORDER BY                       ti datetime DESC               LIMIT 1                 lid        FROM                   SELECT  DISTINCT home               FROM    topten                 t1          ro  topten t2 WHERE  t2 id   ro lid

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Since people seem to keep running into this thread  comment date ranges from 1 5 year  isn t this much simpler   SELECT   FROM  SELECT   FROM topten ORDER BY datetime DESC  tmp GROUP BY home  No aggregation functions needed      Cheers

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You can also try this one and for large tables query performance will be better  It works when there no more than two records for each home and their dates are different   Better general MySQL query is one from Michael La Voie above    SELECT t1 id  t1 home  t1 date  t1 player  t1 resource FROM   t scores 1 t1  INNER JOIN t scores 1 t2    ON t1 home   t2 home WHERE t1 date  gt  t2 date   Or in case of Postgres or those dbs that provide analytic functions try  SELECT t   FROM   SELECT t1 id  t1 home  t1 date  t1 player  t1 resource     row number   over  partition by t1 home order by t1 date desc  rw  FROM   topten t1   INNER JOIN topten t2    ON t1 home   t2 home  WHERE t1 date  gt  t2 date    t WHERE t rw   1

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NOTE  The answer of Michael is perfect for a situation where the target column datetime cannot have duplicate values for each distinct home   If your table has duplicate rows for homexdatetime and you need to only select one row for each distinct home column  here is my solution to it  Your table needs one unique column  like id   If it doesn t  create a view and add a random column to it  Use this query to select a single row for each unique home value  Selects the lowest id in case of duplicate datetime  SELECT tt   FROM topten tt INNER JOIN           SELECT min id  as min id  home from topten tt2     INNER JOIN                    SELECT home  MAX datetime  AS MaxDateTime         FROM topten         GROUP BY home  groupedtt2     ON tt2 home   groupedtt2 home       as groupedtt ON tt id   groupedtt id

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This works on Oracle   with table max as    select id          home          datetime          player          resource          max home  over  partition by home  maxhome     from table     select id        home        datetime        player        resource   from table max  where home   maxhome

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Here is MySQL version which prints only one entry where there are duplicates MAX datetime  in a group   You could test here http   www sqlfiddle com   2 0a4ae 1  Sample Data  mysql gt  SELECT   from topten   ------ ------ --------------------- -------- ----------    id     home   datetime              player   resource    ------ ------ --------------------- -------- ----------       1     10   2009-04-03 00 00 00   john          399        2     11   2009-04-03 00 00 00   juliet        244        3     10   2009-03-03 00 00 00   john          300        4     11   2009-03-03 00 00 00   juliet        200        5     12   2009-04-03 00 00 00   borat         555        6     12   2009-03-03 00 00 00   borat         500        7     13   2008-12-24 00 00 00   borat         600        8     13   2009-01-01 00 00 00   borat         700        9     10   2009-04-03 00 00 00   borat         700       10     11   2009-04-03 00 00 00   borat         700       12     12   2009-04-03 00 00 00   borat         700    ------ ------ --------------------- -------- ----------    MySQL Version with User variable  SELECT   FROM       SELECT ord            IF   prev home   ord home  0  1  AS is first appear           prev home    ord home     FROM           SELECT t1 id  t1 home  t1 player  t1 resource         FROM topten t1         INNER JOIN               SELECT home  MAX datetime  AS mx dt             FROM topten             GROUP BY home             x ON t1 home   x home AND t1 datetime   x mx dt         ORDER BY home       ord   SELECT  prev home    0   seq    0  init   y WHERE is first appear   1   ------ ------ -------- ---------- ----------------- ------------------------    id     home   player   resource   is first appear    prev home    ord home    ------ ------ -------- ---------- ----------------- ------------------------       9     10   borat         700                 1                       10       10     11   borat         700                 1                       11       12     12   borat         700                 1                       12        8     13   borat         700                 1                       13    ------ ------ -------- ---------- ----------------- ------------------------  4 rows in set  0 00 sec    Accepted Answers  outout  SELECT tt   FROM topten tt INNER JOIN           SELECT home  MAX datetime  AS MaxDateTime     FROM topten     GROUP BY home   groupedtt ON tt home   groupedtt home AND tt datetime   groupedtt MaxDateTime  ------ ------ --------------------- -------- ----------    id     home   datetime              player   resource    ------ ------ --------------------- -------- ----------       1     10   2009-04-03 00 00 00   john          399        2     11   2009-04-03 00 00 00   juliet        244        5     12   2009-04-03 00 00 00   borat         555        8     13   2009-01-01 00 00 00   borat         700        9     10   2009-04-03 00 00 00   borat         700       10     11   2009-04-03 00 00 00   borat         700       12     12   2009-04-03 00 00 00   borat         700    ------ ------ --------------------- -------- ----------  7 rows in set  0 00 sec

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SELECT  tt   FROM    TestTable tt  INNER JOIN                    SELECT  coord  MAX datetime  AS MaxDateTime          FROM    rapsa          GROUP BY                 krd            groupedtt ON      tt coord   groupedtt coord         AND tt datetime   groupedtt MaxDateTime

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The fastest MySQL solution  without inner queries and without GROUP BY   SELECT m                      -- get the row that contains the max value FROM topten m                 --  m  from  max      LEFT JOIN topten b        --  b  from  bigger          ON m home   b home    -- match  max  row with  bigger  row by  home          AND m datetime  lt  b datetime           -- want  bigger  than  max  WHERE b datetime IS NULL      -- keep only if there is no bigger than max   Explanation   Join the table with itself using the home column  The use of LEFT JOIN ensures all the rows from table m appear in the result set  Those that don t have a match in table b will have NULLs for the columns of b   The other condition on the JOIN asks to match only the rows from b that have bigger value on the datetime column than the row from m   Using the data posted in the question  the LEFT JOIN will produce this pairs    ------------------------------------------ --------------------------------                 the row from  m                  the matching row from  b       ------------------------------------------ --------------------------------    id  home  datetime     player   resource   id    home   datetime             ---- ----- ------------ -------- --------- ------ ------ ------------ -----    1    10    04 03 2009   john     399       NULL   NULL   NULL                   2    11    04 03 2009   juliet   244       NULL   NULL   NULL                   5    12    04 03 2009   borat    555       NULL   NULL   NULL                   3    10    03 03 2009   john     300       1      10     04 03 2009           4    11    03 03 2009   juliet   200       2      11     04 03 2009           6    12    03 03 2009   borat    500       5      12     04 03 2009           7    13    24 12 2008   borat    600       8      13     01 01 2009           8    13    01 01 2009   borat    700       NULL   NULL   NULL                  ------------------------------------------ --------------------------------    Finally  the WHERE clause keeps only the pairs that have NULLs in the columns of b  they are marked with   in the table above   this means  due to the second condition from the JOIN clause  the row selected from m has the biggest value in column datetime   Read the SQL Antipatterns  Avoiding the Pitfalls of Database Programming book for other SQL tips

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Michae The accepted answer will working fine in most of the cases but it fail for one for as below   In case if there were 2 rows having HomeID and Datetime same the query will return both rows  not distinct HomeID as required  for that add Distinct in query as below   SELECT DISTINCT tt home    tt MaxDateTime FROM topten tt INNER JOIN      SELECT home  MAX datetime  AS MaxDateTime     FROM topten     GROUP BY home  groupedtt  ON tt home   groupedtt home  AND tt datetime   groupedtt MaxDateTime

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

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