Question

我有两张桌子，albums和pictures ...

pictures通过albums与fk_albumID有关。

现在想要尝试从albums中选择所有内容，同时计算与albums有关的图片数量...

我尝试过： SELECT *, (SELECT COUNT(*) FROM pictures WHERE pictures.fk_albumID = albums.albumID) AS albumCount FROM pictures, albums

但是，如果没有图片，这首先不会返回任何结果...... 然后它根据计数重复结果。因此，如果专辑有3张图片，那么当我将它绑定到中继器时，我将在我的列表中获得该专辑3次。

我试过了： SELECT COUNT(albums.albumID) AS albumCount, albums.albumName, albums.albumID FROM albums INNER JOIN pictures ON pictures.fk_albumID = albums.albumID GROUP BY albums.albumID, albums.albuName

但这只显示有照片的专辑......

Answer 1

你虽然很近。您所需要的只是从INNER JOIN到OUTER JOIN

SELECT COUNT(billeder.album_id) AS AlbumSize, 
       albums.album_name, 
       albums.album_id 
  FROM albums 
 LEFT OUTER JOIN billeder 
              ON billeder.album_home = albums.album_id 
 GROUP BY albums.album_id, albums.album_name

Answer 2

您可以使用子查询：

SELECT p.PicCount AS AlbumSize, 
  albums.album_name, 
  albums.album_id 
FROM albums a
INNER JOIN billeder b
  ON b.album_home = a.album_id 
LEFT JOIN 
(
  SELECT count(*) PicCount, fk_albumid
  FROM pictures
  GROUY BY fk_albumid
) p
  on a.album_id = p.fk_albumid

Answer 3

SELECT t1.album_title, isnull(sum(flag),0) AS PicCount
FROM albums AS t1
LEFT JOIN
(
SELECT *, 1 AS Flag
FROM pictures) AS t2
ON t1.fk_albumID = t2.fk_albumID
GROUP BY t1.album_title

链接到SQL Fiddle

Answer 4

SELECT (SELECT COUNT(1)
        FROM billeder
        WHERE billeder.album_home = albums.album_id) albumCount,
       albums.album_name,
       albums.album_id
FROM albums

Answer 5

select 
    AL.album_name, 
    AL.albumID, 
    (select count(*) from 
            ALBUMS AL1, 
            PICTURES PIC1 
     where  AL1.albumID = PIC1.albumID) as CNT_ALBUMID
from 
    ALBUMS AL

试一试

从SQL同时获取内容和计数

5 个答案: