如何從數據庫中獲取唯一記錄？

Question

這是我的表結構

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

問題是我的畫廊太多了。

這是我的mysql查詢

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

這是結果

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

該查詢顯示了畫廊表中的所有記錄，我在查詢中添加了DISTINCT，但無法正常工作。 誰能告訴我我在這里想念的嗎？

Answer 1

如果每個相冊只需要一個圖像（無論如何），則可以使用GROUP BY子句按相冊ID進行分組：

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