胎监不合格吸氧有用吗:ADO.NET中的多数据表操作浅析—修改 - 秋枫思语 - CSDN博客

ADO.NET中的多数据表操作浅析—修改作者：郑佐        2004-8-5
三、更新数据集首先需要说明的是我这里去掉了Order Details表，对两个表的操作只是其中的几个字段。下面是窗体界面：  
图3-1单选框用来选择不同的更新方法。在DataAccess类中增加两个类成员变量：     private SqlDataAdapter _customerDataAdapter; //客户数据适配器     private SqlDataAdapter _orderDataAdapter; //订单数据适配器 customerDataAdapter在构造函数中的初始化为//实例化_customerDataAdapterSqlCommand selectCustomerComm = new SqlCommand("GetCustomer",_conn);selectCustomerComm.CommandType = CommandType.StoredProcedure;selectCustomerComm.Parameters.Add("@CustomerID",SqlDbType.NChar,5,"CustomerID");         SqlCommand insertCustomerComm = new SqlCommand("AddCustomer",_conn);insertCustomerComm.CommandType = CommandType.StoredProcedure;insertCustomerComm.Parameters.Add("@CustomerID",SqlDbType.NChar,5,"CustomerID");insertCustomerComm.Parameters.Add("@CompanyName",SqlDbType.NVarChar,40,"CompanyName");insertCustomerComm.Parameters.Add("@ContactName",SqlDbType.NVarChar,30,"ContactName"); SqlCommand updateCustomerComm = new SqlCommand("UpdateCustomer",_conn);updateCustomerComm.CommandType = CommandType.StoredProcedure;updateCustomerComm.Parameters.Add("@CustomerID",SqlDbType.NChar,5,"CustomerID");updateCustomerComm.Parameters.Add("@CompanyName",SqlDbType.NVarChar,40,"CompanyName");updateCustomerComm.Parameters.Add("@ContactName",SqlDbType.NVarChar,30,"ContactName");              SqlCommand deleteCustomerComm = new SqlCommand("DeleteCustomer",_conn);deleteCustomerComm.CommandType = CommandType.StoredProcedure;deleteCustomerComm.Parameters.Add("@CustomerID",SqlDbType.NChar,5,"CustomerID"); _customerDataAdapter = new SqlDataAdapter(selectCustomerComm);_customerDataAdapter.InsertCommand = insertCustomerComm;_customerDataAdapter.UpdateCommand = updateCustomerComm;_customerDataAdapter.DeleteCommand = deleteCustomerComm; 上面的代码完全可以用设计器生成，觉得有些东西自己写感觉更好，不过代码还是很多。对于_orderDataAdapter的初始化同上面的差不多，这里我们只看订单增加的处理，下面是存储过程：CREATE PROCEDURE  AddOrder (     @OrderID INT OUT,     @CustomerID NCHAR(5),     @OrderDate DATETIME)ASINSERT INTO Orders(     CustomerID ,     OrderDate ) VALUES(     @CustomerID ,     @OrderDate)--SELECT @OrderID = @@IDENTITY  //使用触发器有可能出现问题SET @OrderID = SCOPE_IDENTITY()GO OrderID自动增长值的获取通过输出参数来完成，这个相当不错，如果使用SqlDataAdapter.RowUpdated事件来处理那效率会很低。对insertOrderComm对象的定义为：SqlCommand insertOrderComm = new SqlCommand("AddOrder",_conn);insertOrderComm.CommandType = CommandType.StoredProcedure;insertOrderComm.Parameters.Add("@OrderID",SqlDbType.Int,4,"OrderID");insertOrderComm.Parameters["@OrderID"].Direction = ParameterDirection.Output;insertOrderComm.Parameters.Add("@OrderDate",SqlDbType.DateTime,8,"OrderDate");insertOrderComm.Parameters.Add("@CustomerID",SqlDbType.NChar,5,"CustomerID"); 在实现数据的更新方法之前我们先来明确一些更新逻辑：对于标记为删除的行，先删除订单表的数据，再删除客户表的数据；对于标记为添加的行，先添加客户表的数据，再添加订单表的数据。 （1）实现用获取修改过的DataSet的副本子集来更新数据的方法。这也是调用Xml Web Service更新数据的常用方法，先来看第一个版本，子集的获取通过DataSet.GetChangs方法来完成。//使用数据集子集更新数据public void UpdateCustomerOrders(DatasetOrders ds){                  DataSet dsModified = ds.GetChanges(DataRowState.Modified);//获取修改过的行     DataSet dsDeleted = ds.GetChanges(DataRowState.Deleted);//获取标记为删除的行     DataSet dsAdded = ds.GetChanges(DataRowState.Added);//获取增加的行     try     {             _conn.Open();//先添加客户表数据，再添加订单表数据         if(dsAdded != null)         {              _customerDataAdapter.Update(dsAdded,"Customers");              _orderDataAdapter.Update(dsAdded,"Orders");              ds.Merge(dsAdded);         }         if(dsModified != null)//更新数据表         {              _customerDataAdapter.Update(dsModified,"Customers");              _orderDataAdapter.Update(dsModified,"Orders");              ds.Merge(dsModified);         }         if(dsDeleted != null)//先删除订单表数据，再删除客户表数据         {              _orderDataAdapter.Update(dsDeleted,"Orders");              _customerDataAdapter.Update(dsDeleted,"Customers");              ds.Merge(dsDeleted);         }                       }     catch(Exception ex)     {         throw new Exception("更新数据出错",ex);     }     finally     {         if(_conn.State != ConnectionState.Closed)              _conn.Close();     }}上面的方法看上去比较清晰，不过效率不会很高，至少中间创建了三个DataSet，然后又进行了多次合并。（2）另一方法就是引用更新，不创建副本。相对来说性能会高许多，但是如果用在Web服务上传输的数据量会更大(可以结合两个方法进行改进)。具体的实现就是通过DataTable.Select方法选择行状态来实现。//引用方式更新数据public void UpdateCustomerOrders(DataSet ds){     try     {             _conn.Open();          //先添加客户表数据，再添加订单表数据            _customerDataAdapter.Update(ds.Tables["Customers"].Select("","",DataViewRowState.Added));      _orderDataAdapter.Update(ds.Tables["Orders"].Select("","",DataViewRowState.Added));     //更新数据表       _customerDataAdapter.Update(ds.Tables["Customers"].Select("","",DataViewRowState.ModifiedCurrent));      _orderDataAdapter.Update(ds.Tables["Orders"].Select("","",DataViewRowState.ModifiedCurrent));//先删除订单表数据，再删除客户表数据      _orderDataAdapter.Update(ds.Tables["Orders"].Select("","",DataViewRowState.Deleted));      _customerDataAdapter.Update(ds.Tables["Customers"].Select("","",DataViewRowState.Deleted));                 }     catch(Exception ex)     {         throw new Exception("更新数据出错",ex);     }     finally     {         if(_conn.State != ConnectionState.Closed)              _conn.Close();     }}结合上面的两个方法我们可想到调用Web Service有更合理的方法来完成。（3）使用事务public void UpdateCustomerOrdersWithTransaction(DataSet ds){     SqlTransaction trans = null;     try     {             _conn.Open();         trans = _conn.BeginTransaction();         _customerDataAdapter.DeleteCommand.Transaction = trans;         _customerDataAdapter.InsertCommand.Transaction = trans;         _customerDataAdapter.UpdateCommand.Transaction = trans;         _orderDataAdapter.DeleteCommand.Transaction = trans;         _orderDataAdapter.InsertCommand.Transaction = trans;         _orderDataAdapter.UpdateCommand.Transaction = trans;     _customerDataAdapter.Update(ds.Tables["Customers"].Select("","",DataViewRowState.Added));                   _orderDataAdapter.Update(ds.Tables["Orders"].Select("","",DataViewRowState.Added));     _customerDataAdapter.Update(ds.Tables["Customers"].Select("","",DataViewRowState.ModifiedCurrent));     _orderDataAdapter.Update(ds.Tables["Orders"].Select("","",DataViewRowState.ModifiedCurrent));     _orderDataAdapter.Update(ds.Tables["Orders"].Select("","",DataViewRowState.Deleted));     _customerDataAdapter.Update(ds.Tables["Customers"].Select("","",DataViewRowState.Deleted));            trans.Commit();     }     catch(Exception ex)     {         trans.Rollback();         throw new Exception("更新数据出错",ex);     }     finally     {         if(_conn.State != ConnectionState.Closed)              _conn.Close();     }}最后让我们来看看窗体的按钮更新事件的代码：private void buttonUpdate_Click(object sender, System.EventArgs e){              //提交编辑数据     this.BindingContext[this._ds].EndCurrentEdit();          if(radioButtonRef.Checked == true)//引用方式更新         _dataAccess.UpdateCustomerOrders((DataSet)_ds);     else if(radioButtonTrans.Checked == true)//启用事务更新数据表         _dataAccess.UpdateCustomerOrdersWithTransaction((DataSet)_ds);     else      {         DatasetOrders changedData =  (DatasetOrders)_ds.GetChanges();         if(radioButtonWeb.Checked == true)//Web服务的更正更新         {                                    _dataAccess.UpdateCustomerOrders((DataSet)changedData);         }         else//创建副本合并方式更新         {                                _dataAccess.UpdateCustomerOrders(changedData);         }         //去除订单表中添加的虚拟行         foreach(DataRow row in _ds.Orders.Select("","",DataViewRowState.Added))              _ds.Orders.RemoveOrdersRow((DatasetOrders.OrdersRow)row);         //去除客户表中添加的虚拟行         foreach(DataRow row in _ds.Customers.Select("","",DataViewRowState.Added))              _ds.Customers.RemoveCustomersRow((DatasetOrders.CustomersRow)row);         _ds.Merge(changedData);     }     //提交数据集状态     _ds.AcceptChanges();} 本文参考：《ADO.NET Core Reference》  本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/zhzuo/archive/2004/08/06/67037.aspx