Question

我可以按年份选择总和，这很容易。

就像这样。

var query = from t in ctx.SomeDataEntity
                            group t by t.DateAdded.Year into g
                            select new
                            {
                                Year = g.Year,
                                Total = g.Sum(t => t.SomeColumn1) +
                                g.Sum(t => t.SomeColumn2) +
                                g.Sum(t => t.SomeColumn3) +
                                g.Sum(t => t.SomeColumn4)
                            };

但是，如何按月过滤数据？简单地将t.DateAdded.Year替换为t.DateAdded.Month并不容易，因为t.DateAdded.Month是1,2,3，...，12。我需要的是格式为2014-01,2014-02，...，2014-12。

Answer 1

您可以按年份和月份进行分组：

var query = from t in ctx.SomeDataEntity
                    group t by new 
                    { 
                        Year = t.DateAdded.Year, 
                        Month = t.DateAdded.Month 
                    } into g
                    select new
                    {
                        MonthAndYear = g.Key.Year + "-" + g.Key.Month,
                        Total = g.Sum(t => t.SomeColumn1) +
                        g.Sum(t => t.SomeColumn2) +
                        g.Sum(t => t.SomeColumn3) +
                        g.Sum(t => t.SomeColumn4)
                    };

Answer 2

您可以按月和年分组：

var query = from t in ctx.SomeDataEntity
                        group t by new { Month = t.DateAdded.Month, Year = t.DateAdded.Year } into g
                        select new
                        {
                            Year = g.Key.Year,
                            Month = g.Key.Month,
                            Total = g.Sum(t => t.SomeColumn1) +
                            g.Sum(t => t.SomeColumn2) +
                            g.Sum(t => t.SomeColumn3) +
                            g.Sum(t => t.SomeColumn4)
                        };

Answer 3

试试这个：

var query = from t in ctx.SomeDataEntity
                            group t by new { t.DateAdded.Year, t.DateAdded.Month} into g
                            select new
                            {
                                Year = g.Key.Year,
                                Month = g.Key.Month,
                                Total = g.Sum(t => t.SomeColumn1) +
                                g.Sum(t => t.SomeColumn2) +
                                g.Sum(t => t.SomeColumn3) +
                                g.Sum(t => t.SomeColumn4)
                            };

如何在LINQ中按月汇总数据？

3 个答案: