考慮以下 - 一個標準化的方法...
DROP TABLE IF EXISTS my_table;
CREATE TABLE my_table
(id INT NOT NULL
,d INT NOT NULL
,val INT NOT NULL
,PRIMARY KEY(id,d)
);
INSERT INTO my_table VALUES
(1,1,47),
(2,1,47),
(3,1,0),
(4,1,3),
(5,1,48),
(6,1,49),
(1,2,3),
(2,2,98),
(3,2,99),
(4,2,100),
(5,2,10),
(6,2,12),
(1,3,71),
(2,3,82),
(3,3,3),
(4,3,6),
(5,3,3),
(6,3,4);
SELECT * FROM my_table;
+----+---+-----+
| id | d | val |
+----+---+-----+
| 1 | 1 | 47 |
| 1 | 2 | 3 |
| 1 | 3 | 71 |
| 2 | 1 | 47 |
| 2 | 2 | 98 |
| 2 | 3 | 82 |
| 3 | 1 | 0 |
| 3 | 2 | 99 |
| 3 | 3 | 3 |
| 4 | 1 | 3 |
| 4 | 2 | 100 |
| 4 | 3 | 6 |
| 5 | 1 | 48 |
| 5 | 2 | 10 |
| 5 | 3 | 3 |
| 6 | 1 | 49 |
| 6 | 2 | 12 |
| 6 | 3 | 4 |
+----+---+-----+
SELECT x.*
FROM my_table x
JOIN
(SELECT id,MAX(val) max_val FROM my_table GROUP BY id) y
ON y.id = x.id
AND y.max_val = x.val;
+----+---+-----+
| id | d | val |
+----+---+-----+
| 1 | 3 | 71 |
| 2 | 2 | 98 |
| 3 | 2 | 99 |
| 4 | 2 | 100 |
| 5 | 1 | 48 |
| 6 | 1 | 49 |
+----+---+-----+
(這是打算作爲一個MySQL的解決方案 - 我不熟悉ORACLE語法,所以道歉,如果這沒有端口)
這是否回答您的評論?
SELECT x.* , y.max_val
FROM my_table x
JOIN
(SELECT id,MAX(val) max_val FROM my_table GROUP BY id) y
ON y.id = x.id ;
+----+---+-----+---------+
| id | d | val | max_val |
+----+---+-----+---------+
| 1 | 1 | 47 | 71 |
| 1 | 2 | 3 | 71 |
| 1 | 3 | 71 | 71 |
| 2 | 1 | 47 | 98 |
| 2 | 2 | 98 | 98 |
| 2 | 3 | 82 | 98 |
| 3 | 1 | 0 | 99 |
| 3 | 2 | 99 | 99 |
| 3 | 3 | 3 | 99 |
| 4 | 1 | 3 | 100 |
| 4 | 2 | 100 | 100 |
| 4 | 3 | 6 | 100 |
| 5 | 1 | 48 | 48 |
| 5 | 2 | 10 | 48 |
| 5 | 3 | 3 | 48 |
| 6 | 1 | 49 | 49 |
| 6 | 2 | 12 | 49 |
| 6 | 3 | 4 | 49 |
+----+---+-----+---------+
的MySQL或Oracle?正確標記它。 –
1.看到規範化 – Strawberry
@AhhikChakraborty:它實際上是Oracle數據庫,但我想知道如何在SQL查詢中做到這一點? –