Question

我是SQL的新手，我有三个表：

ALBUMS
album_id | album_name | artist_id | category_id

CATEGORIES
category_id | category_name

ARTISTS
artist_id | artist_name

给定category_name，如何获得category_id, album_id, album_name, artist_id, artist_name的结果集？

我尝试了很多JOIN的变体，但我最终得到了更多的结果，而不是缩小结果。这甚至可能吗？

Answer 1

如果你想要类别“abc”就这样做

Select a.category_id, a.album_id, c.album_name, a.artist_id, a.artist_name
from ALBUMS a
join CATEGORIES b on a.category_id=b.category_id
join ARTISTS c on a.artist_id =c.artist_id
where c.Categoryname='abc'

Answer 2

select ALBUMS.category_id
,      ALBUMS.album_id
,      ALBUMS.album_name
,      ALBUMS.artist_id
,      ARTISTS.artist_name
from   ALBUMS
       inner join ARTISTS on ALBUMS.artist_id = ARTISTS.artist_id
       inner join CATEGORIES on ALBUMS.category_id = CATEGORIES .category_id
where  CATEGORIES.category_name = 'Your category name'

使用SQL连接缩小结果？

2 个答案: