加入3张表排序

我有3张桌子我想放在一起。包含所有用户视频的视频表，包含所有用户图像的图像表和摄像机表。我想列出所有的图片和视频，并与(videoid, userid, cameraid, videosize, datetime, deleted, videolength, videoname)加入3张表排序

prefix_images表(imageid, userid, cameraid, imagesize, datetime, deleted, imagename)

prefix_cameras表(userid, cameraid, ...)

对它们进行排序

prefix_videos表以前我只用了视频表，这个查询了我什么我需要：

SELECT prefix_videos.videoid, prefix_videos.videoname, prefix_videos.videosize, 
prefix_videos.videodatetime, prefix_videos.videolength, prefix_cameras.cameraname FROM 
prefix_videos INNER JOIN prefix_cameras USING (userid,cameraid) WHERE 
prefix_videos.deleted IS NULL AND prefix_videos.userid=xxx ORDER BY 
prefix_videos.datetime DESC

但现在我正在添加一个图像表。所以，我要的是建立一个表：

imageid/videoid, cameraid, imagesize/videosize, datetime (either from image or video table), videoname/imagename

因为我现在结合了图像和视频表给出一个结果，我不知道其他INNER JOIN有道理吗？

这里的另一个重要组成部分是为NULL删除的条目，并通过无论是来自图像或视频的日期顺序对这些能力的检查。

来源

2013-06-22 Tom

您可以分别创建两个选择适合视频和图像，然后用工会把他们聚在一起。凌乱的部分是，你必须经过排序AFAIK

select * from(
SELECT prefix_videos.videoid, prefix_videos.videoname, prefix_videos.videosize, 
    prefix_videos.videodatetime, prefix_videos.videolength, prefix_cameras.cameraname FROM 
    prefix_videos INNER JOIN prefix_cameras USING (userid,cameraid) WHERE 
    prefix_videos.deleted IS NULL AND prefix_videos.userid=xxx ORDER BY 
    prefix_videos.datetime DESC 
    union 
    SELECT prefix_images.imageid, prefix_images.imagename, prefix_images.imagesize, 
    prefix_images.imagesdatetime, prefix_images.videolength, prefix_cameras.cameraname FROM 
    prefix_images INNER JOIN prefix_cameras USING (userid,cameraid) WHERE 
    prefix_images.deleted IS NULL AND prefix_images.userid=xxx ORDER BY 
    prefix_images.datetime DESC 
)a order by 'mycolumn'

或

select imageid/videoid, cameraid, imagesize/videosize, datetime (either from image or video table), videoname/imagename 

from 
(select imageid as 'imageid/videoid', cameraid ,imagesize as 'imagesize/videosize', datetime, imagename as 'videoname/imagename' from prefix_images where ... 
union 
select videoid as 'imageid/videoid', cameraid ,videosize as 'imagesize/videosize', datetime, videoname as 'videoname/imagename' from prefix_videos where ... 
)as temptable 
inner join whatever_your_table on temptable.selected_column=whatever_your_table .equivalent_column 
order by 'mycolumn'

来源

2013-06-22 04:48:32 AdrianBR

这不适合我，我认为是因为列不一样。所以我认为这违反了联盟的规则。仍然试图找出它...... – Tom

你可以使用cast（）将不同的列转换为不同的类型。 – AdrianBR

总之，是的，你可以加入JOIN后加入。语法通常看起来像

select [stuff] from [tableA] 
join [tableB] 
on [tableA.column] = [tableB.column] 
join [tableC] 
on [tableAorTableB.column] = [tableC.column] 
where [conditions]

等等。我简单化了，但你明白了。

来源

2013-06-22 03:18:21 catfood

啊，真正的问题是-should-我做了三路连接，不-can- I. AdrianBR在这里有更好的答案。 – catfood

加入3张表排序

回答

相关问题