SQL转化Linq
麻烦大神把SQL转化为Linq，万分感激，在线等，谢谢。。。

select dis.ProductId,pro.ProductName,pho.Photo,SUM(case when dis.MsgContent<>'' or dis.MsgImage<>'' or dis.MsgSound<>'' then 1 else 0 end)msgcount
 from Discuss dis,ProductInfo pro,ProductPhoto pho
 where dis.ProductId=pro.ID and dis.ProductId=pho.ProductID
group by dis.ProductId,pro.ProductName,pho.Photo

var query = from dis in Discuss
            from pro in ProductInfo
            from pho in ProductPhoto
            where dis.ProductId == pro.ID && dis.ProductId == pho.ProductID
            group new { dis, pro, pho } by new { dis.ProductId, pro.ProductName, pho.Photo } into g
            select new { Key.dis.ProductId, Key.pro.ProductName, Key.pho.Photo,
                         msgcount = g.Sum(x => (x.dis.MsgContent <> "" 
[解决办法]
 x.dis.MsgImage <> "" 
[解决办法]
 x.dis.MsgSound <> "") ? 1 : 0) };