linq to sql 学习（7）linq的分组汇总操作

来源：互联网发布：老虎证券是人工智能编辑：程序博客网时间：2024/05/22 03:23

这里我们主要是介绍LINQ TO SQL 中，分组Group by 在LINQ TO SQL 中的使用。

我们先创建两个cs 类。

/// <summary>

/// 手机列表

/// </summary>

public class MobileStore

{

public string mobId

{ set; get; }

public string mobName

{ set; get; }

}

/// <summary>

/// 手机销售表

/// </summary>

public class MobileSale

{

public string Sid

{ set; get; }

public string mobId

{ set; get; }

public string mobName

{ set; get; }

public string price

{ set; get; }

}

List<MobileStore> listStore = new List<MobileStore>();

listStore.Add(new MobileStore { mobId = "1", mobName = "N86" });

listStore.Add(new MobileStore { mobId = "2", mobName = "N82" });

listStore.Add(new MobileStore { mobId = "3", mobName = "N81" });

listStore.Add(new MobileStore { mobId = "4", mobName = "N95" });

listStore.Add(new MobileStore { mobId = "5", mobName = "N85" });

List<MobileSale> listSale = new List<MobileSale>();

listSale.Add(new MobileSale { Sid="1" ,mobId="1",mobName="N86",price="100"});

listSale.Add(new MobileSale { Sid="2", mobId = "2", mobName = "N82",price="220" });

listSale.Add(new MobileSale { Sid="3", mobId = "2", mobName = "N82",price="200" });

listSale.Add(new MobileSale { Sid = "4", mobId = "3", mobName = "N81", price = "300" });

//Sum函数的使用

var querySum =

from m in listSale group m by m.mobId into g

select new

{

g.Key,

总价格= g==null ? 0 : g.Sum(a=>Convert.ToInt32(a.price))

};

返回的结果：

//Max函数的使用

var queryMax = from m in listSale group m by m.mobId into g

select new

{

g.Key,

最大价格 = g==null ? 0 : g.Max(a=>Convert.ToInt32(a.price))

};

返回的结果：

//Min函数的使用

var queryMin = from m in listSale

group m by m.mobId into g

select new

{

g.Key,

最小价格 = g == null ? 0 : g.Min(a => Convert.ToInt32(a.price))

};

返回的结果：

//Avg函数的使用

var queryAvg = from m in listSale

group m by m.mobId into g

select new

{

g.Key,

平均价格 = g == null ? 0 : g.Average(a => Convert.ToInt32(a.price))

};

返回的结果：

gd.Dataource = queryMin;

gd.DataBind();