Data Entry With the DataRow



ADO.NET provides different types of support for data entry into a table. For example, you can use the classic INSERT INTO expression from the SQL. You can also create a stored procedure that internally creates a new record. Besides the INSERT expression or a stored procedure, to perform data entry, you can use a DataSet object.

The DataSet class is equipped with a Tables property, which is a collection of the tables that are part of the data set. The Tables property is an object of type DataTableCollection. As its name indicates, the DataTableCollection itself is a list of tables and each table can be located using an index, either by the numeric order of the table or its name. The DataTableCollection class supports this through an Item property which is based on the DataTable class. This relationship makes it possible to access the contents of a table. Fundamentally, a table is made of columns and records and each record is also called a row.

The records of a table are stored in a member of the DataTable called Rows. The Rows property is an object of type DataRowCollection. An individual record is an object of type DataRow. To represent each record, the DataRowCollection is equipped with an Item property which is of type DataRow. To perform data entry, you can assign a value to the name of each column of the desired table of your database. Each column is accessible through the Item property of the DataRow class. One of the overloaded versions of this property takes a String value as its index.

After assigning the right value to each DataRow::Item that corresponds to the desired column of a table, you can call the Update() method of the data adapter you were using. This means that, previously, you should have initialized a data adapter.

Practical Learning Practical Learning: Performing Data Entry With DataRow 

  1. Start Microsoft Visual C++ .NET or Microsoft Visual Studio .NET
  2. In Server Explorer, expand the Servers, the name of the server, and the SQL Servers nodes. Expand the name of the server. If you see a database named CarInventory, fine. If not, To create a new database, right-click the name of the server and click New Database. Set the name of the database to CarInventory and click OK 
  3. Expand the new CarInventory node. To create a new table, right-click the Tables node and click New Table
  4. Complete the table as follows:
    Column Name Data Type Length Allow Nulls Properties
    CarID int     Primary Key
    Identity: Yes
    TagNumber varchar 20 Unchecked  
    Make varchar 40 Unchecked  
    Model varchar 40 Unchecked  
    CarYear varchar 20 Unchecked  
    Category varchar 40 Unchecked  
    HasK7Player bit      
    HasCDPlayer bit      
    HasDVDPlayer bit      
    CarPicture varchar 240    
    IsAvailable bit      
  5. Save the table as Cars and close it
  6. On the main menu of Visual Studio .NET, click File -> New -> Project
  7. In the Project Types list, select Microsoft Visual C++ Projects. In the Templates list, click Windows Forms Application
  8. Set the Name to CarInventory2 and click OK
  9. Design the form as follows: 
    Control Text Name Other Properties
    Label Text #    
    TextBox   txtTagNumber  
    Label Make:    
    TextBox   txtMake  
    Label Model:    
    TextBox   txtModel  
    Label Year:    
    TextBox   txtYear  
    Label Category:    
    ComboBox   cboCategory DropDownStyle: DropDownList
    Items: Economy
    Full Size
    Mini Van
    CheckBox Cassete Player chkK7Player CheckAlign: MiddleRight
    CheckBox DVD Player chkDVDPlayer CheckAlign: MiddleRight
    CheckBox CD Player chkCDPlayer CheckAlign: MiddleRight
    CheckBox Available chkAvailable CheckAlign: MiddleRight
    PictureBox   pctCar SizeMode: CenterImage
    Button Picture btnPicture  
    TextBox   txtPicture  
    Button Add Car btnAddCar  
    Button Close btnClose DialogResult: OK
    Form     AcceptButton: btnAddCar
    MaximizeBox: False
    StartPosition: CenterScreen
  10. In the Windows Forms section of the Toolbox, click the OpenFileDialog button and click the form
  11. Set its Filter as Picture Files (*.bmp;*.gif;*.jpeg;*jpg)|*.bmp;*.gif;*.jpeg;*jpg
  12. Set its Title to Select Car Picture
  13. On the form, double-click the Picture button and implement its event as follows:
    private: System::Void btnPicture_Click(System::Object *  sender, System::EventArgs *  e)
    	 if( openFileDialog1->ShowDialog() == DialogResult::OK )
    		 this->txtPicture->Text = openFileDialog1->FileName;
    		 this->pctCar->Image = Bitmap::FromFile(openFileDialog1->FileName);
  14. From Server Explorer, open the server that holds the above database then expand the CarInventory database followed by the Tables node
  15. Drag the Cars table and drop it on the form
  16. On the main menu, click Data -> Generate Dataset...
  17. While the New radio button is selected, change the name of the dataset to dsCarInventory and click OK
  18. Double-click an empty area of the form and change the Load event as follows:
    private: System::Void Form1_Load(System::Object *  sender, System::EventArgs *  e)
  19. Return to the form and double-click the Add Car followed by the Close buttons
  20. Implement the events as follows:
    private: System::Void btnAddCar_Click(System::Object *  sender, System::EventArgs *  e)
    	 DataTable *tblCars = new DataTable;
    	 tblCars = this->dsCarInventory1->Tables->Item[S"Cars"];
    	 DataRow __gc *rowNewCar;
    	 rowNewCar = tblCars->NewRow();
    	 rowNewCar->Item[S"TagNumber"] = this->txtTagNumber->Text;
    	 rowNewCar->Item[S"Make"]      = this->txtMake->Text;
    	 rowNewCar->Item[S"Model"]     = this->txtModel->Text;
    	 rowNewCar->Item[S"CarYear"]   = this->txtYear->Text;
    	 rowNewCar->Item[S"Category"]  = this->cboCategory->Text;
    	 rowNewCar->Item[S"HasK7Player"]  = this->chkK7Player->Checked.ToString();
    	 rowNewCar->Item[S"HasCDPlayer"]  = this->chkCDPlayer->Checked.ToString();
    	 rowNewCar->Item[S"HasDVDPlayer"] = this->chkDVDPlayer->Checked.ToString();
    	 rowNewCar->Item[S"CarPicture"]   = this->txtPicture->Text;
    	 rowNewCar->Item[S"IsAvailable"]  = this->chkAvailable->Checked.ToString();
    	 this->txtTagNumber->Text    = S"";
    	 this->txtMake->Text         = S"";
    	 this->txtModel->Text        = S"";
    	 this->txtYear->Text         = S"";
    	 this->cboCategory->SelectedIndex = -1;
    	 this->chkK7Player->Checked  = false;
    	 this->chkCDPlayer->Checked  = false;
    	 this->chkDVDPlayer->Checked = false;
    	 this->txtPicture->Text      = S"";
    	 this->chkAvailable->Checked = false;
    	 this->pctCar->Image = 0;
    private: System::Void btnClose_Click(System::Object *  sender, System::EventArgs *  e)
  21. Execute the application and create a record (you can first download a few pictures of cars):
  22. Click Add Car to submit the record
  23. Click Close to close the form



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