選擇最新一個從每個類別

Question

：

id | cat_id | name | date 
------------------------------------ 
1 | 1  | suzy | 2011-09-15 
2 | 2  | andy | 2011-10-01 
3 | 1  | dony | 2010-12-25 
4 | 3  | harry | 2010-01-05 
5 | 2  | matty | 2011-06-01 
6 | 3  | samy | 2010-11-02 
7 | 1  | honey | 2011-10-03 

如何選擇，如果我想要得到這樣的：

cat_id | id | 
------------- 
1 | 7 | 
2 | 2 | 
3 | 6 | 

Answer 1

SELECT cat_id, id 
    FROM mytable t 
WHERE NOT EXISTS (
     SELECT * 
      FROM mytable 
     WHERE cat_id = t.cat_id 
      AND date > t.date 
     ) 

Answer 2

SELECT cat_id, id 
FROM (SELECT cat_id, name 
     FROM table 
     ORDER BY date DESC) AS h 
GROUP BY cat_id 
ORDER BY cat_id ASC 

更換table

Answer 3

試試看s查詢 -

SELECT c1.cat_id, c1.id FROM catalog c1 
    JOIN (SELECT cat_id, MAX(date) last_date FROM catalog GROUP BY cat_id) c2 
    ON c1.cat_id = c2.cat_id AND c1.date = c2.last_date;