select app.appname,art.*
from spiderapps app
left join (select content_url,title,read_num,biz,ROW_NUMBER() over(partition by biz order by read_num desc)rn from spiderarticles )art on art.biz=app.biz and art.rn=1
order by read_num desc
var groups = spiderarticles.GroupBy(s => s.biz).Select(s => s.OrderByDescending(x => x.read_num).FirstOrDefault());
var result = from app in spiderapps
join art in groups on app.biz equals art.biz
orderby app.read_num descending
select new { app.appname, art.biz, art.…… };
