sql - SQL查询艺术家、专辑和歌曲

Question

我有个问题...

在 MS Access 中，我有一个表单，您可以在其中搜索艺术家、专辑和歌曲。现在我想查询搜索结果，但不确定是否可以。这是我的数据库的示例：

现在我想搜索艺术家、专辑和歌曲。当它找到艺术家时，我希望专辑和编号列为空。当它创建一个专辑时，我想填写艺术家和专辑列，数字行必须为空。当它找到一首歌时，我希望填满所有 3 列

这有可能吗？

标签： sqlms-access

Answer 1

您可以使用union all：

select id as artist_id, name as artist_name,
       null as album_id, null as album_name,
       null as track_id, null as track_name
from artists
where . . .    -- your conditions here
union all
select null as artist_id, null as artist_name,
       id as album_id, name as album_name,
       null as track_id, null as track_name
from albums
where . . .    -- your conditions here
union all
select null as artist_id, null as artist_name,
       null as album_id, null as album_name,
       id as track_id, name as track_name
from tracks
where . . .    -- your conditions here