计入与左外连接相连的两个表

Question

我需要一点SQL查询帮助。我想计算两个表中的条目数。我的第一个名为tracking_adspace_views的表从我制作的Adspace的每个视图中输入。在一天结束时，我想计算我上一天有多少参赛作品。第二个表tracking_clicks计算特殊广告空间的点击次数。因此，并非每个被查看的广告空间都有点击次数。所以最后我想要像

这样的东西

• Adspace Id 1有500次观看和3次点击
• Adspace Id 2有340次观看和0次点击
• 等......

我的表格看起来像这样

tracking_adspace_views

tracking_clicks

我的查询如下：

SELECT  '2013-10-31', 
        views.tracking_adspace, 
        COUNT(views.tracking_adspace) AS tracking_adspace_views,                        
        COUNT(clicks.tracking_adspace) AS tracking_adspace_clicks
FROM views
LEFT JOIN (
            SELECT tracking_adspace, 
                   COUNT(sub_c.tracking_adspace) AS tracking_adspace_clicks
            FROM tracking_clicks as sub_c
            GROUP BY sub_c.tracking_adspace
          ) AS clicks 
       ON clicks.tracking_adspace = views.tracking_adspace
WHERE views.tracking_time LIKE  '2013-10-31%'
GROUP BY views.tracking_adspace

正确计算视图，点击次数为0的计数也是正确的。但如果点击列中有点击，我会从视图中获取值。谢谢你的帮助：）

此致

Answer 1

您似乎正在计算将由连接重复的行中的值。

尝试这样的事情： -

SELECT  '2013-10-31' AS TrackingDate, 
        views.tracking_adspace, 
        COUNT(views.tracking_adspace) AS tracking_adspace_views,                        
        clicks.tracking_adspace_clicks
FROM views
LEFT JOIN 
(
    SELECT tracking_adspace, 
            DATE(tracking_time) AS TrackingDate,
            COUNT(tracking_adspace) AS tracking_adspace_clicks
    FROM tracking_clicks 
    GROUP BY tracking_adspace
) AS clicks 
ON clicks.tracking_adspace = views.tracking_adspace
AND DATE(views.tracking_time) = clicks.TrackingDate
WHERE DATE(views.tracking_time) = '2013-10-31'
GROUP BY TrackingDate, views.tracking_adspace, clicks.tracking_adspace_clicks

Answer 2

我希望你有一个名为tracking_adspaces的第三个表，或者一个名为tracking_adspace的主键。如果你这样做，你可以这样做：

select  '2013-10-13' as TrackingDate,
        A.tracking_adspace
        V.views,
        C.clicks
from tracking_adspaces A
left join (
        select tracking_adspace, count(tracking_id) as views
        from views
        where DATE(tracking_time) = '2013-10-31'
        group by tracking_adspace
) V on A.tracking_adspace = V.tracking_adspace
left join (
        select tracking_adspace, count(tracking_id) as clicks
        from tracking_clicks
        where DATE(tracking_time) = '2013-10-31'
        group by tracking_adspace
) C on A.tracking_adspace = C.tracking_adspace

如果没有，您可以使用

select  '2013-10-13' as TrackingDate,
        distinct(A.tracking_adspace)
        V.views,
        C.clicks
from views A
left join ( 
(etc)