使用linq对多个进行分组[重复]

Posted 2023-03-31

【中文标题】使用linq对多个进行分组[重复]

【英文标题】：Group BY multiple using linq [duplicate]

【发布时间】：2016-07-20 06:19:08

【问题描述】：

尝试按多个文件分组，但遇到问题。我想按时间段、产品代码分组。

var ProductUsageSummary = from b in myProductUsage
                            group b by b.ProductCode into g
                            select new
                            
                                Period = g.Key,
                                Code = g.Key,
                                Count = g.Count(),
                                TotalQty = g.Sum(n => n.Qty),
                                Price = g.Average(n => n.Price)
                            ;

也试过

var ProductUsageSummary = from b in myProductUsage
                            group b by b.Period b.ProductCode into g
                            select new
                            
                                Period = g.Key(n => n.period),
                                Code = g.Key,
                                Count = g.Count(),
                                TotalQty = g.Sum(n => n.Qty),
                                Price = g.Average(n => n.Price)
                            ;

【参考方案1】：

您可以创建一个匿名对象来对多列进行分组（例如...new prop1 prop2），Key.PropertyName 可以访问分组的字段

试试这个。

var ProductUsageSummary = from b in myProductUsage
                          group b by new  b.Period,  b.ProductCode into g
                          select new
                          
                              Period= g.Key.Period,
                              Code = g.Key.ProductCode ,
                              Count = g.Count(),
                              TotalQty = g.Sum(n => n.Qty),
                              Price = g.Average(n => n.Price)
                          ;

【参考方案2】：

这是使用匿名类型的正确语法：

group b by new  b.ProductCode, b.Period  into g

然后在选择中：

g.Key.ProductCode 和 g.Key.Period

完整查询：

var ProductUsageSummary = from b in myProductUsage
                          group b by new  b.Period b.ProductCode  into g
                          select new
                          
                              Period = g.Key.Period,
                              Code = g.Key.ProductCode,
                              Count = g.Count(),
                              TotalQty = g.Sum(n => n.Qty),
                              Price = g.Average(n => n.Price)
                          ;