linq到具有聚合函数的SQL

SELECT ItemCode, AVG([Count]) As [Count]
FROM [tblHistory]
GROUP BY ItemCode
ORDER BY [Count] desc

tblHistory

{ ItemCode(int), Count(int), Date(datetime) }

 var query = from p in Context.tblHistories
             group p by p.ItemCode into g
             select new tblHistory
                        {
                            ItemCode = g.Key,
                            Count = from c in g select new { c.Count }
                        };

tblHistories.GroupBy(p => p.ItemCode)
         .Select(g => new { ItemCode = g.Key, Count = g.Average (c => c.Count)})
         .OrderByDescending(x => x.Count)
         .AsEnumerable()
         .Select(x => new tblHistory{ ItemCode = x.ItemCode, Count = (int)x.Count })