HOWTO: Add Records and Edit Data in a DBGrid Cell

• Microsoft Visual Basic Standard, Professional, and Enterprise Editions, 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

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: By clicking this button, you create
            ' a database with four fields and five records.
   
            Set db = CreateDatabase("C:\test.mdb", dbLangGeneral)
            Set td = db.CreateTableDef("Table1")
   
            ' After you create the database, you need to add fields to it.
            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 you have added fields to the database, you need to 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, add
                  rs1("Field " & CStr(iFields)) = CStr(iFields) ' 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: By clicking this button, you save
            ' the contents of the text box to the database. Since the contents
            ' of the recordset are being modified, the contents are saved to
            ' the database after you execute 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: By clicking this button, you execute
            ' 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, you
            ' must modify the underlying recordset from the Data control.
   
            Data1.UpdateControls
         End Sub
   
         Private Sub Command4_Click()
            ' The Add New Record button: By clicking this button, you add 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 an 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 control. The contents of the text box will be added as a new record.

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Issue type : kbhowto