Linq语法

1.一对多关系查询：var q=from c in db.Students      from n in c.orders      where c.City=='wuhan'      select  n;2.多对多关系查询： var q=from e in db.Students       from et in e.name       where e.city=='wuhan'       select new           {             e.firstName,             e.lastName           }3.where 简单形式查询  var q=from c in db.students     where c.city=="hhh"     select c;条件筛选： var q=from c in db.students     where c.sex>=5     select c;4.first(实质就是sql中top1)简单用法：选择表中的第一个发货方。Shipper shipper = db.Shippers.First();选择CustomerID 为“BONAP”的单个客户Customer cust = db.Customers.First(c => c.CustomerID == "BONAP");5.匿名函数：  var q =    from c in db.Customers    select new {c.ContactName, c.Phone};  使用 SELECT 和匿名类型返回仅含客户联系人姓名和电话号码的序列；6.where 和order by形式：  var q =    from o in db.Orders    where o.ShipCity == "London"    orderby o.Freight    select o;7.Concat（连接）简单形式： 返回所有消费者和雇员的电话和传真  var q = (         from c in db.Customers         select c.Phone        ).Concat(         from c in db.Customers         select c.Fax        ).Concat(         from e in db.Employees         select e.HomePhone        ); Union（合并）8.插入(Insert)：：：：NorthwindDataContext db = new NorthwindDataContext();var newCustomer = new Customer{    CustomerID = "MCSFT",    CompanyName = "Microsoft",    ContactName = "John Doe",    ContactTitle = "Sales Manager",    Address = "1 Microsoft Way",    City = "Redmond",    Region = "WA",    PostalCode = "98052",    Country = "USA",    Phone = "[phone]",    Fax = null};db.Customers.InsertOnSubmit(newCustomer);db.SubmitChanges();9.更新update：:::  Customer cust =db.Customers.First(c => c.CustomerID == "ALFKI");    cust.ContactTitle = "Vice President";    db.SubmitChanges();10.删除delete::::::   OrderDetail orderDetail =    db.OrderDetails.First(c => c.OrderID == 10255 && c.ProductID == 36);    db.OrderDetails.DeleteOnSubmit(orderDetail);    db.SubmitChanges();