ex-14-06

Programming Csharp Source Code(代码) Programming Csharp Source Code

         this.Controls.Add (this.txtCompanyID);
         this.Controls.Add (this.label1);
         this.Controls.Add (this.btnNew);
         this.Controls.Add (this.txtCustomerName);
         this.Controls.Add (this.btnUpdate);
         this.Controls.Add (this.lblMessage);
         this.Controls.Add (this.btnDelete);
         this.Controls.Add (this.lbCustomers);
      }

      // handle the new button click
      protected void btnNew_Click (object sender, System.EventArgs e)
      {
         // create a new row, populate it
         DataRow newRow = dataTable.NewRow();
         newRow["CustomerID"] = txtCompanyID.Text;
         newRow["CompanyName"] = txtCompanyName.Text;
         newRow["ContactName"] = txtContactName.Text;
         newRow["ContactTitle"] = txtContactTitle.Text;
         newRow["Address"] = txtAddress.Text;
         newRow["City"] = txtCity.Text;
         newRow["PostalCode"] = txtZip.Text;
         newRow["Phone"] = txtPhone.Text;

         // add the new row to the table
         dataTable.Rows.Add(newRow);


         // the following lines create an explicit insert command object
         string connectionString = 
            "server=YourServer; uid=sa; pwd=YourPassword; database=northwind";
         System.Data.SqlClient.SqlConnection connection = new System.Data.SqlClient.SqlConnection(connectionString);
         connection.Open();

         System.Data.SqlClient.SqlCommand insertCommand = new System.Data.SqlClient.SqlCommand();
         insertCommand.CommandText = "Insert into customers values(" +
            "'" + newRow["CustomerID"] + "', " +
            "'" + newRow["CompanyName"] + "', " +
            "'" + newRow["ContactName"] + "', " +
            "'" + newRow["ContactTitle"] + "', " +
            "'" + newRow["Address"] + "', " +
            "'" + newRow["City"] + "', " +
            "''," +
            "'" + newRow["PostalCode"] + "', " +
            "''," +
            "'" + newRow["Phone"] + "', '')";
         insertCommand.Connection = connection;

         DataAdapter.InsertCommand = insertCommand;


         // update the db
         DataAdapter.Update(DataSet,"Customers"); 

         // inform the user and accept the changes
         lblMessage.Text = "Updated!";
         Application.DoEvents();
         DataSet.AcceptChanges();

         // repopulate the list box
         PopulateLB();

         // clear all the text fields
         ClearFields();
      }

      // set all the text fields to empty strings
      private void ClearFields()
      {
         txtCompanyID.Text = "";
         txtCompanyName.Text = "";
         txtContactName.Text = "";
         txtContactTitle.Text = "";
         txtAddress.Text = "";
         txtCity.Text = "";
         txtZip.Text = "";
         txtPhone.Text = "";
      }

      // handle the update button click
      protected void btnUpdate_Click (object sender, System.EventArgs e)
      {
         // get the selected row
         DataRow targetRow  = dataTable.Rows[lbCustomers.SelectedIndex];

         // inform the user
         lblMessage.Text = "Updating " +  targetRow["CompanyName"];
         Application.DoEvents();

         // edit the row
         targetRow.BeginEdit(); 
         targetRow["CompanyName"] = txtCustomerName.Text;
         targetRow.EndEdit();

         // get each row that changed
         DataSet DataSetChanged = 
            DataSet.GetChanges(DataRowState.Modified);


         // test to make sure all the changed rows are without errors
         bool okayFlag = true;
         if (DataSetChanged.HasErrors)
         {
            okayFlag = false;
            string msg = "Error in row with customer ID "; 

            // examine each table in the changed DataSet
            foreach (DataTable theTable in DataSetChanged.Tables)
            {
               // if any table has errors, find out which rows
               if (theTable.HasErrors)
               {
                  // get the rows with errors
                  DataRow[] errorRows = theTable.GetErrors();

                  // iterate through the errors and correct
                  // (in our case, just identify)
                  foreach (DataRow theRow in errorRows)
                  {
                     msg = msg + theRow["CustomerID"];
                  }
               }
            }
            lblMessage.Text = msg;
         }
         // if we have no errors
         if (okayFlag)
         {
            // merge the changes back into the original DataSet
            DataSet.Merge(DataSetChanged);

            // the following lines create an explicit update command object
            string connectionString = 
               "server=YourServer; uid=sa; pwd=YourPassword; database=northwind";
            System.Data.SqlClient.SqlConnection connection = new System.Data.SqlClient.SqlConnection(connectionString);
            connection.Open();


            System.Data.SqlClient.SqlCommand updateCommand = new System.Data.SqlClient.SqlCommand();
            string updateCmd = "Update Customers set CompanyName = '" + 
               targetRow["CompanyName"].ToString() + "' where CustomerID = '" +
               targetRow["CustomerID"].ToString() + "'";
            updateCommand.CommandText = updateCmd;

            updateCommand.Connection = connection;

            DataAdapter.UpdateCommand = updateCommand;

            // update the database
            DataAdapter.Update(DataSet,"Customers"); 

            // inform the user
            lblMessage.Text = DataAdapter.UpdateCommand.CommandText;
            Application.DoEvents();

            // accept the changes and repopulate the list box
            DataSet.AcceptChanges();
            PopulateLB();
         }
         else  // if we had errors, reject the changes
            DataSet.RejectChanges();
      }


      // handle the delete button click
      protected void btnDelete_Click (object sender, System.EventArgs e)
      {
         // get the selected row
         DataRow targetRow  = dataTable.Rows[lbCustomers.SelectedIndex];
         string custID = targetRow["CustomerID"].ToString();


         // prepare message for user
         string msg = targetRow["CompanyName"] + " deleted. ";

         // delete the selected row
         dataTable.Rows[lbCustomers.SelectedIndex].Delete();

         // accept the changes to the DataSet
         DataSet.AcceptChanges();

         // the following lines create an explicit insert command object
         string connectionString = 
            "server=YourServer; uid=sa; pwd=YourPassword; database=northwind";

         System.Data.SqlClient.SqlConnection connection = new System.Data.SqlClient.SqlConnection(connectionString);
         connection.Open();


         System.Data.SqlClient.SqlCommand deleteCommand = new System.Data.SqlClient.SqlCommand();
         deleteCommand.CommandText = "delete from customers where customerID = " +
            "'" + custID + "'";
         deleteCommand.Connection = connection;

         DataAdapter.DeleteCommand = deleteCommand;


         // update the database
         DataAdapter.Update(DataSet,"Customers"); 

         // repopulate the list box without the deleted record
         PopulateLB();

         // inform the user
         lblMessage.Text = msg;
         Application.DoEvents();
      }

      public static void Main(string[] args) 
      {
         Application.Run(new ADOForm1());
      }
   }
}