EF 求和 GroupBy多个字段

GroupBy根据多个字段分组使用方式：

一、使用扩展方法

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)
});

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)
    });


二、Linq方式

[csharp] view plain copy print ?

var query = from l in list
group l by new { l.Name, l.BatNum } into g
select new
{
Name = g.Key.Name,
Count = g.Sum(a => a.Count),
BatNum = g.Key.BatNum
};

        var query = from l in list  
                    group l by new { l.Name, l.BatNum } into g  
                    select new  
                    {  
                        Name = g.Key.Name,  
                        Count = g.Sum(a => a.Count),  
                        BatNum = g.Key.BatNum  
                    };

三、生成KeyValue类型

[csharp] view plain copy print ?

Dictionary<string,decimal> buildList = _build.FindList().GroupBy(q => q.SaleCode)
.Select(q => new { Code = q.Key, ReaAmount = q.Sum(i => i.RealAmount) })
.ToDictionary(q => q.Code, q => q.ReaAmount);

1）单个字段Group by：

[c#] view plain copy print ?

//a.Key类型与a.Province字段类型一样
.GroupBy(a => a.Province).Select(a => a.Key).ToList();

//a.Key类型与a.Province字段类型一样
.GroupBy(a => a.Province).Select(a => a.Key).ToList();

2）多个字段Group by：

[c#] view plain copy print ?

//此时返回的数据列表需要自己转换
.GroupBy(a => new { a.Date, a.Week }).Select(a => a.Key).ToList();

//此时返回的数据列表需要自己转换
.GroupBy(a => new { a.Date, a.Week }).Select(a => a.Key).ToList();

3）单个字段Order by：

[c#] view plain copy print ?

.OrderBy(a => a.Date).ToList()

.OrderBy(a => a.Date).ToList()

4）多个字段Order by：

[c#] view plain copy print ?

.OrderBy(a => a.Date).ThenBy(a => a.EndTime).ThenBy(a => a.StartTime).ToList()

.OrderBy(a => a.Date).ThenBy(a => a.EndTime).ThenBy(a => a.StartTime).ToList()

5）多个字段Order by倒序：

[c#] view plain copy print ?

.OrderByDescending(a => a.Date).ThenByDescending(a => a.EndTime).ThenByDescending(a => a.StartTime).ToList()

.OrderByDescending(a => a.Date).ThenByDescending(a => a.EndTime).ThenByDescending(a => a.StartTime).ToList()

http://blog.csdn.net/u011127019/article/details/54943303

原文出处：http://www.itdos.com/CSharp/20150409/0153322.html