Sql="Select a.*,(Select Count(aa.VideoID) from [tbl_ALLVideo] as aa inner join [tbl_AllUser] as bb on aa.UserName=bb.UserName where bb.Province=a.ProvinceName) as Num from [tbl_Province] as a order by Num desc"
分析什么呀 Select a.*,(Select Count(aa.VideoID) from [tbl_ALLVideo] as aa inner join [tbl_AllUser] as bb on aa.UserName=bb.UserName where bb.Province=a.ProvinceName) as Num from [tbl_Province] as a order by Num desc
括号中间是aa与bb关联获取aa.VideoID的count值?count值是不是一个数字? (后面……实在不懂,又和tbl_Province有关系……。现在暂缺数据库文件,无法详细说明。) 现只想问一句,()as Num ,Num是一个具体的数字值吗?ps:count ,as ,inner join 都是头一次接触,见晾
Select a.*,(Select Count(aa.VideoID)
from [tbl_ALLVideo] as aa inner join [tbl_AllUser] as bb on aa.UserName=bb.UserName
where bb.Province=a.ProvinceName) as Num
from [tbl_Province] as a order by Num desc
(后面……实在不懂,又和tbl_Province有关系……。现在暂缺数据库文件,无法详细说明。)
现只想问一句,()as Num ,Num是一个具体的数字值吗?ps:count ,as ,inner join 都是头一次接触,见晾
as num ,是把前的计算 结果 当一个列,列名是num
tbl_ALLVideo:保存视频;aa
tbl_AllUser:保存用户;bb
tbl_Province:保存省份;a
该sql语句的功能是,获取各省的视频数量,按数量降序排列。终于弄懂了,学到了