说明:调用DeleteOnSubmit方法便可。数据库
OrderDetail orderDetail = db.OrderDetails.First (c => c.OrderID == 10255 && c.ProductID == 36); db.OrderDetails.DeleteOnSubmit(orderDetail); db.SubmitChanges();
语句描述:使用DeleteOnSubmit方法从OrderDetail 表中删除OrderDetail对象。调用SubmitChanges 将此删除保持到数据库。ui
说明:Order与OrderDetail是一对多关系,首先DeleteOnSubmit其OrderDetail(多端),其次DeleteOnSubmit其Order(一端)。由于一端是主键。spa
var orderDetails = from o in db.OrderDetails where o.Order.CustomerID == "WARTH" && o.Order.EmployeeID == 3 select o; var order = (from o in db.Orders where o.CustomerID == "WARTH" && o.EmployeeID == 3 select o).First(); foreach (OrderDetail od in orderDetails) { db.OrderDetails.DeleteOnSubmit(od); } db.Orders.DeleteOnSubmit(order); db.SubmitChanges();
语句描述语句描述:使用DeleteOnSubmit方法从Order 和Order Details表中删除Order和Order Detail对象。首先从Order Details删除,而后从Orders删除。调用SubmitChanges将此删除保持到数据库。code
说明:Order与OrderDetail是一对多关系,在上面的例子,咱们所有删除CustomerID为WARTH和EmployeeID为3 的数据,那么咱们不须所有删除呢?例如Order的OrderID为10248的OrderDetail有不少,可是咱们只要删除ProductID为11的OrderDetail。这时就用Remove方法。对象
Order order = db.Orders.First(x => x.OrderID == 10248); OrderDetail od = order.OrderDetails.First(d => d.ProductID == 11); order.OrderDetails.Remove(od); db.SubmitChanges();
语句描述语句描述:这个例子说明在实体对象的引用实体将该对象从其EntitySet 中移除时,推理删除如何致使在该对象上发生实际的删除操做。仅当实体的关联映射将DeleteOnNull设置为true且CanBeNull 为false 时,才会发生推理删除行为。 blog
说明:在对于在不一样的DataContext之间,使用Attach方法来更新数据。例如在一个名为tempdb的NorthwindDataContext中,查询出Customer和Order,在另外一个NorthwindDataContext中,Customer的地址更新为123 First Ave,Order的CustomerID 更新为CHOPS。ip
//一般,经过从其余层反序列化 XML 来获取要附加的实体 //不支持将实体从一个DataContext附加到另外一个DataContext //所以若要复制反序列化实体的操做,将在此处从新建立这些实体 Customer c1; List<Order> deserializedOrders = new List<Order>(); Customer deserializedC1; using (NorthwindDataContext tempdb = new NorthwindDataContext()) { c1 = tempdb.Customers.Single(c => c.CustomerID == "ALFKI"); deserializedC1 = new Customer { Address = c1.Address, City = c1.City, CompanyName = c1.CompanyName, ContactName = c1.ContactName, ContactTitle = c1.ContactTitle, Country = c1.Country, CustomerID = c1.CustomerID, Fax = c1.Fax, Phone = c1.Phone, PostalCode = c1.PostalCode, Region = c1.Region }; Customer tempcust = tempdb.Customers.Single(c => c.CustomerID == "ANTON"); foreach (Order o in tempcust.Orders) { deserializedOrders.Add(new Order { CustomerID = o.CustomerID, EmployeeID = o.EmployeeID, Freight = o.Freight, OrderDate = o.OrderDate, OrderID = o.OrderID, RequiredDate = o.RequiredDate, ShipAddress = o.ShipAddress, ShipCity = o.ShipCity, ShipName = o.ShipName, ShipCountry = o.ShipCountry, ShippedDate = o.ShippedDate, ShipPostalCode = o.ShipPostalCode, ShipRegion = o.ShipRegion, ShipVia = o.ShipVia }); } } using (NorthwindDataContext db2 = new NorthwindDataContext()) { //将第一个实体附加到当前数据上下文,以跟踪更改 //对Customer更新,不能写错 db2.Customers.Attach(deserializedC1); //更改所跟踪的实体 deserializedC1.Address = "123 First Ave"; //附加订单列表中的全部实体 db2.Orders.AttachAll(deserializedOrders); //将订单更新为属于其余客户 foreach (Order o in deserializedOrders) { o.CustomerID = "CHOPS"; } //在当前数据上下文中提交更改 db2.SubmitChanges(); }
语句描述:从另外一个层中获取实体,使用Attach和AttachAll将反序列化后的实体附加到数据上下文,而后更新实体。更改被提交到数据库。it
说明:在不一样的DataContext中,实现插入、更新、删除。看下面的一个例子:io
//一般,经过从其余层反序列化XML获取要附加的实体 //此示例使用 LoadWith 在一个查询中预先加载客户和订单, //并禁用延迟加载 Customer cust = null; using (NorthwindDataContext tempdb = new NorthwindDataContext()) { DataLoadOptions shape = new DataLoadOptions(); shape.LoadWith<Customer>(c => c.Orders); //加载第一个客户实体及其订单 tempdb.LoadOptions = shape; tempdb.DeferredLoadingEnabled = false; cust = tempdb.Customers.First(x => x.CustomerID == "ALFKI"); } Order orderA = cust.Orders.First(); Order orderB = cust.Orders.First(x => x.OrderID > orderA.OrderID); using (NorthwindDataContext db2 = new NorthwindDataContext()) { //将第一个实体附加到当前数据上下文,以跟踪更改 db2.Customers.Attach(cust); //附加相关订单以进行跟踪; 不然将在提交时插入它们 db2.Orders.AttachAll(cust.Orders.ToList()); //更新客户的Phone. cust.Phone = "2345 5436"; //更新第一个订单OrderA的ShipCity. orderA.ShipCity = "Redmond"; //移除第二个订单OrderB. cust.Orders.Remove(orderB); //添加一个新的订单Order到客户Customer中. Order orderC = new Order() { ShipCity = "New York" }; cust.Orders.Add(orderC); //提交执行 db2.SubmitChanges(); }
语句描述:从一个上下文提取实体,并使用 Attach 和 AttachAll 附加来自其余上下文的实体,而后更新这两个实体,删除一个实体,添加另外一个实体。更改被提交到数据库。class