ADO.NET中的多數據表操作淺析—修改 - 中國WEB開發者網絡 (http://www.webasp.net) -- 技術教程 (http://www.webasp.net/article/) --- ADO.NET中的多數據表操作淺析—修改 (http://www.webasp.net/article/13/12456.htm) |
| -- 作者：未知 -- 發佈日期： 2004-08-21 |
| ADO.NET中的多數據表操作淺析—修改
作者：鄭佐??????? 2004-8-5 三、更新數據集 首先需要說明的是我這裡去掉了Order Details表，對兩個表的操作只是其中的幾個字段。下面是窗體界面： 圖3-1 單選框用來選擇不同的更新方法。 在DataAccess類中增加兩個類成員變量： ???? private SqlDataAdapter _customerDataAdapter; //客戶數據適配器 ???? private SqlDataAdapter _orderDataAdapter; //訂單數據適配器 ? customerDataAdapter在構造函數中的初始化為 //實例化_customerDataAdapter SqlCommand 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; ? 上面的代碼完全可以用設計器生成，覺得有些東西自己寫感覺更好，不過代碼還是很多。 對於_orderDataAdapter的初始化同上面的差不多，這裡我們只看訂單增加的處理，下面是存儲過程： CREATE PROCEDURE? AddOrder ( ???? @OrderID INT OUT, ???? @CustomerID NCHAR(5), ???? @OrderDate DATETIME ) AS INSERT INTO Orders ( ???? CustomerID , ???? OrderDate ) VALUES ( ???? @CustomerID , ???? @OrderDate ) --SELECT @OrderID = @@IDENTITY SET @OrderID = SCOPE_IDENTITY() GO ? OrderID自動增長值的獲取通過輸出參數來完成，這個相當不錯，如果使用SqlDataAdapter.RowUpdated事件來處理那效率會很低。 對insertOrderComm對象的定義為： 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"); ? 在實現數據的更新方法之前我們先來明確一些更新邏輯： 對於標記為刪除的行，先刪除訂單表的數據，再刪除客戶表的數據； 對於標記為添加的行，先添加客戶表的數據，再添加訂單表的數據。 ? （1）實現用獲取修改過的DataSet的副本子集來更新數據的方法。 這也是調用Xml Web Service更新數據的常用方法，先來看第一個版本，子集的獲取通過DataSet.GetChangs方法來完成。 //使用數據集子集更新數據 public void UpdateCustomerOrders(DatasetOrders ds) {???????????? ???? DataSet dsModified = ds.GetChanges(DataRowState.Modified);//獲取修改過的行 ???? DataSet dsDeleted = ds.GetChanges(DataRowState.Deleted);//獲取標記為刪除的行 ???? DataSet dsAdded = ds.GetChanges(DataRowState.Added);//獲取增加的行 ???? try ???? {??? ???????? _conn.Open();//先添加客戶表數據，再添加訂單表數據 ???????? if(dsAdded != null) ???????? { ????????????? _customerDataAdapter.Update(dsAdded,"Customers"); ????????????? _orderDataAdapter.Update(dsAdded,"Orders"); ????????????? ds.Merge(dsAdded); ???????? } ???????? if(dsModified != null)//更新數據表 ???????? { ???????? ???? _customerDataAdapter.Update(dsModified,"Customers"); ????????????? _orderDataAdapter.Update(dsModified,"Orders"); ????????????? ds.Merge(dsModified); ???????? } ???????? if(dsDeleted != null)//先刪除訂單表數據，再刪除客戶表數據 ???????? { ????????????? _orderDataAdapter.Update(dsDeleted,"Orders"); ????????????? _customerDataAdapter.Update(dsDeleted,"Customers"); ????????????? ds.Merge(dsDeleted); ???????? }????????????????? ???? } ???? catch(Exception ex) ???? { ???????? throw new Exception("更新數據出錯",ex); ???? } ???? finally ???? { ???????? if(_conn.State != ConnectionState.Closed) ????????????? _conn.Close(); ???? } } 上面的方法看上去比較清晰，不過效率不會很高，至少中間創建了三個DataSet，然後又進行了多次合併。 （2）另一方法就是引用更新，不創建副本。 相對來說性能會高許多，但是如果用在Web服務上傳輸的數據量會更大(可以結合兩個方法進行改進)。具體的實現就是通過DataTable.Select方法選擇行狀態來實現。 //引用方式更新數據 public void UpdateCustomerOrders(DataSet ds) { ???? try ???? {??? ???????? _conn.Open(); ???????? //先添加客戶表數據，再添加訂單表數據 ???? _customerDataAdapter.Update(ds.Tables["Customers"].Select("","",DataViewRowState.Added)); ???? _orderDataAdapter.Update(ds.Tables["Orders"].Select("","",DataViewRowState.Added)); ???? //更新數據表 ???? _customerDataAdapter.Update(ds.Tables["Customers"].Select("","",DataViewRowState.ModifiedCurrent)); ???? _orderDataAdapter.Update(ds.Tables["Orders"].Select("","",DataViewRowState.ModifiedCurrent)); //先刪除訂單表數據，再刪除客戶表數據 ???? _orderDataAdapter.Update(ds.Tables["Orders"].Select("","",DataViewRowState.Deleted)); ???? _customerDataAdapter.Update(ds.Tables["Customers"].Select("","",DataViewRowState.Deleted));??????????? ???? } ???? catch(Exception ex) ???? { ???????? throw new Exception("更新數據出錯",ex); ???? } ???? finally ???? { ???????? if(_conn.State != ConnectionState.Closed) ????????????? _conn.Close(); ???? } } 結合上面的兩個方法我們可想到調用Web Service有更合理的方法來完成。 （3）使用事務 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("更新數據出錯",ex); ???? } ???? finally ???? { ???????? if(_conn.State != ConnectionState.Closed) ????????????? _conn.Close(); ???? } } 最後讓我們來看看窗體的按鈕更新事件的代碼： private void buttonUpdate_Click(object sender, System.EventArgs e) { ????????????? //提交編輯數據 ???? this.BindingContext[this._ds].EndCurrentEdit(); ???? ???? if(radioButtonRef.Checked == true)//引用方式更新 ???????? _dataAccess.UpdateCustomerOrders((DataSet)_ds); ???? else if(radioButtonTrans.Checked == true)//啟用事務更新數據表 ???????? _dataAccess.UpdateCustomerOrdersWithTransaction((DataSet)_ds); ???? else ???? { ???????? DatasetOrders changedData =? (DatasetOrders)_ds.GetChanges(); ???????? if(radioButtonWeb.Checked == true)//Web服務的更正更新 ???????? {????????????????????? ????????????? _dataAccess.UpdateCustomerOrders((DataSet)changedData); ???????? } ???????? else//創建副本合併方式更新 ???????? {????????????????? ????????????? _dataAccess.UpdateCustomerOrders(changedData); ???????? } ???????? //去除訂單表中添加的虛擬行 ???????? foreach(DataRow row in _ds.Orders.Select("","",DataViewRowState.Added)) ????????????? _ds.Orders.RemoveOrdersRow((DatasetOrders.OrdersRow)row); ???????? //去除客戶表中添加的虛擬行 ???????? foreach(DataRow row in _ds.Customers.Select("","",DataViewRowState.Added)) ????????????? _ds.Customers.RemoveCustomersRow((DatasetOrders.CustomersRow)row); ???????? _ds.Merge(changedData); ???? } ???? //提交數據集狀態 ???? _ds.AcceptChanges(); } ? 本文參考：《ADO.NET Core Reference》 歡迎交流：(秋楓的Blog)http://blog.csdn.net/zhzuo ? ? ? |
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