Question

说我有一个歌曲数据库。

ARTIST          |        SONG
-------------------------------------
Cloud Cult        The Meaning of 8
Cloud Cult        Pretty Voice
Jason Alexander   Today Was a Good Day
Jason Alexander   Like a Virgin
Jason Alexander   It Wasn't Me
Powderfinger      Like a Dog

我想要做的是发出一个查询，选择限制为20位艺术家的所有歌曲。不仅仅有20个数据库记录，还有20位艺术家的歌曲。所以在上面的例子中，如果我限制为2，我将获得5个结果，所有歌曲都由Cloud Cult和Jason Alexander的所有歌曲。

这是SQL可以做的吗？

Answer 1

您需要根据所需艺术家的数量创建艺术家的子查询和LIMIT子查询：

SQL Fiddle

MySQL 5.5.32架构设置：

CREATE TABLE Table1
    (`ARTIST` varchar(15), `SONG` varchar(20))
;

INSERT INTO Table1
    (`ARTIST`, `SONG`)
VALUES
    ('Cloud Cult', 'The Meaning of 8'),
    ('Cloud Cult', 'Pretty Voice'),
    ('Jason Alexander', 'Today Was a Good Day'),
    ('Jason Alexander', 'Like a Virgin'),
    ('Jason Alexander', 'It Wasn''t Me'),
    ('Powderfinger', 'Like a Dog')
;

查询1 ：

select t.* 
from (select distinct ARTIST from table1 LIMIT 2) a 
INNER JOIN table1 t on a.ARTIST = t.ARTIST

<强> Results ：

|          ARTIST |                 SONG |
|-----------------|----------------------|
|      Cloud Cult |     The Meaning of 8 |
|      Cloud Cult |         Pretty Voice |
| Jason Alexander | Today Was a Good Day |
| Jason Alexander |        Like a Virgin |
| Jason Alexander |         It Wasn't Me |

Answer 2

Select * FROM LibraryTable lt 
WHERE lt.artist IN (SELECT 
                    DISTINCT lt2.artist 
                    FROM LibraryTable lt2 LIMIT ***X***)

X 是您的艺术家限制。

Answer 3

您可以使用group by function选择特定数据，这是代码

select table1.artist, table1.song from 
(select artist from table1
  group by artist limit 2) t1 
inner join table1 on t1.artist=table1.artist

我可以通过特定列的唯一计数进行限制吗？

3 个答案: