EF多字段求和（分組/不分組）

分組多字段求和

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)
    });

不分組多字段求和（這樣得到的就是對應字段的總的求和，其實還是利用了分組，不過給分組依據傳個空，如果利用linq的話就是傳個常數）

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();