EF多字段求和（分组/不分组）

分组多字段求和

query.GroupBy(q => new { q.Year, q.Month })
    .Select(q => new
    {
        Year = q.Key.Year,
        Month = q.Key.Month,
        BuildAmount = q.Sum(i => i.BuildAmount),
        RecAmount = q.Sum(i => i.RecAmount),
        Amount = q.Sum(i => i.Amount),
        RealAmount = q.Sum(i => i.RealAmount)
    });

不分组多字段求和（这样得到的就是对应字段的总的求和，其实还是利用了分组，不过给分组依据传个空，如果利用linq的话就是传个常数）

where.GroupBy(x => new { }).Select(q => new
                {
                    sumWeight = q.Sum(x => x.Weight),
                    sumQuantity = q.Sum(x => x.Quantity),
                    sumIncome = q.Sum(x => x.Income)
                }).FirstOrDefault();