EF多字段求和（分组/不分组）

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)
    });

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();