Adding Records and Editing Data in a DBGrid Cell

• Standard, Professional, and Enterprise Editions of Microsoft Visual Basic, 16-bit and 32-bit, for Windows, version 4.0

SUMMARY

This article describes how to programmatically edit the data and add new records to a DBGrid control. You can change the contents of a cell and those changes will appear on the screen, but they are not written to the data source bound to the DBGrid control. To write these changes to the data source, you must instead edit the underlying recordset.

MORE INFORMATION

The following example creates a simple database containing one table with four fields and five records. Each record is a number in the field. The database is going to be the data source.

When you click on a cell, the data in that cell is shown in a TextBox. When you change the contents of that cell, the changes are shown on the DBGrid control. However, when you execute the UpdateControls method through a command button, the changes disappear from the cell, indicating the data source was not updated.

You must click the Update Recordset button when you make your changes in the TextBox to ensure that the changes are written to the data source. The Update Recordset button updates the underlying recordset of the Data control. Since the DBGrid control is bound to the Data control, the changes appear in the DBGrid control.

Creating the Sample Application

The following sample application demonstrates how to edit the contents of a DBGrid cell:

1. Start Visual Basic. Once it is running, on the File menu, click New Project. Add a Data control, a DBGrid control, a TextBox, and three Command buttons. Set the following properties for each control:

      Control       Default Name       Property       Value
      -----------------------------------------------------
   
      DBGrid        DBGrid1            DataSource     Data1
   
   

2. Copy the following code sample to the Form1 code window:

         Option Explicit
         Dim rs1 As Recordset
         Dim db As Database
         Dim td As TableDef
         Dim fl As Field
         Dim igRow As Integer, igColumn As Integer
         Dim iFields As Integer, iRecords As Integer
         Dim vargBookmark As Variant
   

         Private Sub Command1_Click()
            'The Create Database button. Clicking this button creates a
            'database with four fields and five records.
   
            Set db = CreateDatabase("C:\test.mdb", dbLangGeneral)
            Set td = db.CreateTableDef("Table1")
   
            'Now that the database is created, add fields to the database
            For iFields = 1 To 4 'The last number can be changed to the number
                                 'of fields you want in the database.
               Set fl = td.CreateField("Field " & CStr(iFields), dbText)
               td.Fields.Append fl
            Next iFields
   
            db.TableDefs.Append td
   
            'Now that the database has fields, add some records through
            'a recordset
            Set rs1 = db.OpenRecordset("Table1", dbOpenTable)
            For iRecords = 1 To 5  'For each row
               rs1.AddNew          'Add a new record
   
               For iFields = 1 To 4            'For each field in the record
                  rs1("Field " & CStr(iFields)) = CStr(iFields)  'Add a number
               Next iFields
   
            rs1.Update
            Next iRecords
   
            'Close both the recordset and database
            rs1.Close
            db.Close
   
            'Populate the DBGrid control with the contents of the Recordset
            Set db = OpenDatabase("C:\test.mdb")
            Set rs1 = db.OpenRecordset("Select * from Table1")
            Set Data1.Recordset = rs1
   
            Command1.Visible = False
            Command2.Visible = True
            Command4.Visible = True
         End Sub
   
         Private Sub Command2_Click()
            'The Update Database button. Clicking this button saves the
   

         'of the text box to the database. Since the contents of the

         'is being modified, the contents are saved to the database after
         'executing the Update method.

         Data1.Recordset.Edit
         Data1.Recordset.Fields(igColumn) = Text1.Text
         Data1.Recordset.Update
      End Sub

      Private Sub Command3_Click()
         'The Update DBGrid button. Clicking this button executes the
         'UpdateControls method on the Data control to demonstrate that
         'changing the cell in a bound DBGrid control does not save
         'the new information to the database. To save these changes,
         'the underlying recordset from the Data control must be modified.

         Data1.UpdateControls
      End Sub

      Private Sub Command4_Click()
         'The Add New Record button. Clicking this button adds new records
         'to the recordset. Use the following code to add a new record to
         'the DBGrid control.

         'Set DBGrid and Data Control Properties to
         'allow new records to be added
         DBGrid1.AllowAddNew = True
         Data1.EOFAction = vbAddNew
         Data1.Recordset.MoveLast
         Data1.Recordset.MoveNext
         DBGrid1.Row = DBGrid1.VisibleRows - 1
         Data1.Recordset.AddNew
         For iFields = 1 To 4                'For each field in the record
            'Add the contents of the text box
            Data1.Recordset("Field " & CStr(iFields)) = Text1.Text
         Next iFields
         Data1.Recordset.Update

      End Sub

      Private Sub DBGrid1_Change()
         Command3.Visible = True
      End Sub

      Private Sub DBGrid1_MouseUp(Button As Integer, Shift As Integer, _
                                  X As Single, Y As Single)
         Command2.Visible = True
         igColumn = DBGrid1.ColContaining(X)
         igRow = DBGrid1.RowContaining(Y)
         vargBookmark = DBGrid1.RowBookmark(igRow)

         Text1.Text = DBGrid1.Columns(igColumn).CellValue(vargBookmark)

      End Sub

      Private Sub Form_Load()
         Command1.Visible = False
         Command2.Visible = False
         Command3.Visible = False
         Command4.Visible = False
         Command1.Caption = "Create Database"
         Command2.Caption = "Update Database"
         Command3.Caption = "Update DBGrid"
         Command4.Caption = "Add New Record"

         'If the database does not exist, show the
         'Create Database button
         If Dir("C:\test.mdb") = "" Then
            Command1.Visible = True
         Else
            'Open existing database
            Set db = OpenDatabase("C:\test.mdb")
            Set rs1 = db.OpenRecordset("Select * from Table1")
            Set Data1.Recordset = rs1
            Command4.Visible = True
         End If

      End Sub

      Private Sub Text1_Change()
         Command2.Visible = True
      End Sub

Running the Sample Application

1. On the Run menu, click Start, or press F5.

2. Click on a cell on the DBGrid control and change the contents of that cell. Click the Update DBGrid button. Note that your changes disappear from the DBGrid. Clicking on a blank area on the DBGrid control gives error 6148 - Invalid row number.

3. Click on a cell. Note that the contents of the cell appear on the TextBox. Change the contents of the TextBox and then click the Update Recordset button. Note that your changes now appear on the DBGrid control.

4. Click the Add New Records button to add a new record to the DBGrid