首先我们还是先建立一个person.cs类
public class person { public string name { get; set; } public int age { get; set; } public string sex { get; set; } }
接下来我们往这个person类添加数据：
List plist1 = new List(); plist1.Add(new person { name = "cxx1", age = 24, sex = "男" }); plist1.Add(new person { name = "www.baidu.com", age = 25, sex = "男" }); plist1.Add(new person { name = "www.52mvc.com", age = 26, sex = "男" }); List plist2 = new List(); plist2.Add(new person { name = "cxx1", age = 24, sex = "男" }); plist2.Add(new person { name = "cxx2", age = 28, sex = "男" }); plist2.Add(new person { name = "cxx4", age = 27, sex = "男" }); plist2.Add(new person { name = "cxx5", age = 28, sex = "男" }); // asp.net var query = from person p in plist1 join person per in plist2 on p.name equals per.name select new { 名称=p.name, 性别=p.sex, 年龄=p.age }; gd2.DataSource = query; gd2.DataBind();
返回的结果是：
备注：这个方法是要查找出 plist1 与 plist2
之中，name名称有相同记录的数据。
接下来我们来看看sql中的左连接left join 在linq中如何实现
还是先来创建两个cs
类。
/// /// 手机列表 /// public class MobileStore { public string mobId { set; get; } public string mobName { set; get; } }
/// 手机销售表 /// public class MobileSale { public string Sid { set; get; } public string mobId { set; get; } public string mobName { set; get; } public string price { set; get; } } List listStore = new List(); 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" }); listStore.Add(new MobileStore { mobId = "6", mobName = "N97" }); List listSale = new List(); 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 = "3", mobName = "N81", price = "300" }); var query = from MobileStore m in listStore join MobileSale sale in listSale on m.mobId equals sale.mobId into joinm from j in joinm.DefaultIfEmpty() select new { ID = m.mobId, 名称 = m.mobName, 价格 = j == null ? "暂无数据" : j.price, }; gd.DataSource = query; gd.DataBind();