Question

我有这个查询，我想计算一个未包含在查询中的字段，我不知道如何。我想要计算的字段被称为＆＃34; pic_id＆＃34;从表photo_comment

SELECT users_pics.wardrobe,
       profile.fname,
       users_pics.pic,
       users_pics.u_pic_id,
       users_pics.email,
       users_pics.make,
       users_pics.designer,
       photo_comment.comment  
FROM dbo.users_pics 
INNER JOIN profile      
ON users_pics.email = profile.email  
LEFT Join (             
      SELECT pic_id, 
             MAX(comment_id) max_comment_id
      FROM photo_comment              
      GROUP BY pic_id
) max_photo_comment 
ON users_pics.u_pic_id = max_photo_comment.pic_id         
LEFT JOIN photo_comment 
ON max_photo_comment.pic_id = photo_comment.pic_id AND max_photo_comment.max_comment_id = photo_comment.comment_id
WHERE users_pics.wardrobe = MMColParam AND users_pics.email = MMColParam2
ORDER BY u_pic_id asc

Answer 1

我假设您想知道“pic”有多少评论。我已将“COUNT（pic_id）count_pic_id”添加到左连接中的子查询中。希望这会有所帮助。

SELECT users_pics.wardrobe, 
 profile.fname,
 users_pics.pic,
 users_pics.u_pic_id,
 users_pics.email,
 users_pics.make,
 users_pics.designer,
 photo_comment.comment,
 max_photo_comment.count_pic_id

FROM dbo.users_pics 
INNER JOIN profile ON users_pics.email = profile.email  
LEFT Join (SELECT pic_id, MAX(comment_id) max_comment_id, COUNT(pic_id) count_pic_id
           FROM photo_comment
           GROUP BY pic_id) max_photo_comment 
    On users_pics.u_pic_id = max_photo_comment.pic_id         
LEFT Join photo_comment On max_photo_comment.pic_id = photo_comment.pic_id 
    AND max_photo_comment.max_comment_id = photo_comment.comment_id
WHERE users_pics.wardrobe = MMColParam AND users_pics.email = MMColParam2
ORDER BY u_pic_id asc

Answer 2

您想计算一个不在您的选择列表中的字段吗？您需要将列添加到选择列表中以便对其进行计数，以及是否要查看计数值。

Select profile.fname,users_pics.pic,users_pics.u_pic_id,users_pics.email,
      users_pics.make,users_pics.designer,photo_comment.comment 
FROM dbo.users_pics 
     INNER JOIN profile      ON users_pics.email = profile.email  
     LEFT Join (SELECT  Count(DISTINCT  pic_id)  pic_id_cnt, pic_id, MAX(comment_id)       max_comment_id
FROM photo_comment              
GROUP BY pic_id         ) max_photo_comment On users_pics.u_pic_id = max_photo_comment.pic_id         
    LEFT Join photo_comment On  max_photo_comment.pic_id = photo_comment.pic_id AND    max_photo_comment.max_comment_id = photo_comment.comment_id
WHERE users_pics.wardrobe = MMColParam AND users_pics.email = MMColParam2
ORDER BY u_pic_id asc

将计数列添加到分组查询

2 个答案: