Question

我想列出仅有独特持有人的前6名比赛记录。我的意思是列表中的持有人不应该与他的另一个记录一起列出。我目前使用下面的查询列出前6次。

mysql> select * from racerecords order by record_time asc, date asc;
+----+---------+------------+-------------+---------------------+----------+
| id | race_id | holder     | record_time | date                | position |
+----+---------+------------+-------------+---------------------+----------+
|  2 |      10 | Stav       |          15 | 2014-08-11 19:43:49 |        1 |
|  1 |      10 | Jennifer   |          15 | 2014-08-13 19:43:19 |        1 |
|  4 |      10 | Jennifer   |          16 | 2014-08-02 19:44:27 |        1 |
|  5 |      10 | Osman      |          17 | 2014-08-04 19:44:57 |        1 |
|  7 |      10 | Gokhan     |          18 | 2014-08-15 19:45:37 |        1 |
|  3 |      10 | MotherLode |          25 | 2014-08-01 19:44:11 |        1 |
+----+---------+------------+-------------+---------------------+----------+
6 rows in set (0.00 sec)

正如你可以看到持有人＆＃34; Jennifer＆＃34;列出两次。我希望mySQL在进入列表后跳过她。我想要生成的结果是：

+----+---------+------------+-------------+---------------------+----------+
| id | race_id | holder     | record_time | date                | position |
+----+---------+------------+-------------+---------------------+----------+
|  2 |      10 | Stav       |          15 | 2014-08-11 19:43:49 |        1 |
|  1 |      10 | Jennifer   |          15 | 2014-08-13 19:43:19 |        1 |
|  5 |      10 | Osman      |          17 | 2014-08-04 19:44:57 |        1 |
|  7 |      10 | Gokhan     |          18 | 2014-08-15 19:45:37 |        1 |
|  3 |      10 | MotherLode |          25 | 2014-08-01 19:44:11 |        1 |
+----+---------+------------+-------------+---------------------+----------+

我尝试了一切。 GROUP BY holder会产生错误的结果。它获得了持有者的第一个记录，即使不是最好的。在此表中，它会生成如上所示的输出，因为 id：1 是我为Jennifer插入的第一条记录。

如何生成输出结果如上？

Answer 1

通过此查询可以实现所需的结果，但性能密集。我已在SQLFilddle http://sqlfiddle.com/#!2/f8ee7/3

中复制了结果

select * from racerecords
where 
(HOLDER, RECORD_TIME) in (
 select HOLDER,min(RECORD_TIME) from racerecords
group by HOLDER)

似乎你错过了在子查询中包含Where子句。试试这个

select * from racerecords
where 
(HOLDER, RECORD_TIME) in (
 select HOLDER,min(RECORD_TIME) from racerecords where race_id =17
group by HOLDER )
And race_id =17
Order by RECORD_TIME

Answer 2

你应该使用distinct子句

    SELECT DISTINCT column_name,column_name
    FROM table_name;

查看此http://www.w3schools.com/sql/sql_distinct.asp

列出具有唯一列的结果

2 个答案: