对艺术家，专辑和歌曲的SQL查询

Question

我有问题...

在MS Access中，我有一个表格，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，但不确定是否可行。这是我的数据库的示例：

现在，我要搜索歌手，专辑和歌曲。找到艺术家后，我希望专辑和编号栏为空。当找到专辑时，我要填写艺术家和专辑列，并且数字行必须为空。当它找到一首歌时，我希望所有3列都填满

这有可能吗？

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