mysql - 如何从数据库中获取唯一记录？

Question

这是我的表结构

album
id ---- albumname
1   General
3   Sports
9   Activities
gallery
id --- ablumid--- image_thumb  --              image_full
1   1   uploads/1358401616.jpg  uploads/thumbs/thumb_1358401616.jpg
2   1   uploads/1358401641.jpg  uploads/thumbs/thumb_1358401641.jpg
3   1   uploads/1358402071.jpg  uploads/thumbs/thumb_1358402071.jpg
4   3   uploads/1358402334.jpg  uploads/thumbs/thumb_1358402334.jpg

问题是我有太多的图片，一个画廊都放不下。

这是我的mysql查询

SELECT DISTINCT gl.catid as gallery_cat_id, ab.albumname,gl.imagest 
FROM albums as ab 
INNER JOIN gallery as gl  ON ab.id=gl.catid 
order by ab.albumname ASC

这是结果

gallery_id  albumname   image_full
38      Activities       uploads/thumbs/thumb_1358424428.jpg
41      Activities       uploads/thumbs/thumb_1358424483.jpg
40      Activities       uploads/thumbs/thumb_1358424468.jpg
39      Activities       uploads/thumbs/thumb_1358424446.jpg

查询显示我在查询中添加 DISTINCT 的图库表中的所有记录，但它不起作用。谁能告诉我我在这里错过了什么？

Answer 1

如果每个相册只需要一张图片(不管是什么)，您可以使用 GROUP BY 子句，按相册 ID 分组:

SELECT gl.catid as gallery_cat_id, ab.albumname, gl.imagest 
FROM
  albums as ab 
  INNER JOIN gallery as gl
  ON ab.id=gl.catid 
GROUP BY ab.id
order by ab.albumname ASC