linq之group by 的使用

group by

 var list = from s in _sysBll.GetList(s => s.ParamID == "TraSchType" && s.ParamCode != null)
                join t in data on s.ParamCode equals t.TraSchType
                group s by s.ParamCode into temp    //如果是多个字段分组{s.paramcode,s.paramId}
                select new
                {
                    ParamCode = temp.Key,//key代表分组字段，如果有多个分组字段，则由key.字段名
                    name = temp.Max(t=>t.ParamDescn),
                    value=temp.Count()
                };