VB.NET ทำปุ่ม Check All ใน Header ของ DataGridView ครับ

    Private Sub PopulateData()

        '*** BindData From Database **'
        Dim objConn As OleDbConnection
        Dim dtAdapter As OleDbDataAdapter
        Dim dt As New DataTable

        Dim strConnString As String
        strConnString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=mydatabase.mdb"
        objConn = New OleDbConnection(strConnString)
        objConn.Open()

        Dim strSQL As String
        strSQL = "SELECT * FROM customer"

        dtAdapter = New OleDbDataAdapter(strSQL, objConn)
        dtAdapter.Fill(dt)

        dtAdapter = Nothing
        objConn.Close()
        objConn = Nothing

        Me.myDgv.DataSource = dt

        '******************************'
        Me.myDgv.Columns.Clear()

        With myDgv.ColumnHeadersDefaultCellStyle
            .BackColor = Color.Navy
            .ForeColor = Color.White
            .Font = New Font(songsDataGridView.Font, FontStyle.Bold)
        End With

        Dim ColumnTextBox As DataGridViewTextBoxColumn




        '*** Column (Select) ***'
        Dim ColumnCheckBox As New DataGridViewCheckBoxColumn()
        ColumnCheckBox.Width = 30
        ColumnCheckBox.DataPropertyName = "Select"
        Me.myDgv.Columns.Add(ColumnCheckBox)

        '*** Checkbox in Header ***'
        Dim ckBox As New CheckBox()
        Dim rect As Rectangle = myDgv.GetCellDisplayRectangle(0, -1, True)
        ckBox.Size = New Size(18, 18)
        rect.X = rect.Location.X + (rect.Width / 4)
        ckBox.Location = rect.Location
        AddHandler ckBox.CheckedChanged, New EventHandler(AddressOf ckBox_CheckedChanged)
        Me.myDgv.Controls.Add(ckBox)

        myDgv.Columns(0).Frozen = False

        '*** Column (CustomerID) ***'
        ColumnTextBox = New DataGridViewTextBoxColumn()
        ColumnTextBox.DataPropertyName = "CustomerID"
        ColumnTextBox.HeaderText = "CustomerID"
        ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
        ColumnTextBox.Width = 100
        Me.myDgv.Columns.Add(ColumnTextBox)

        '*** Column (Name) ***'
        ColumnTextBox = New DataGridViewTextBoxColumn()
        ColumnTextBox.DataPropertyName = "Name"
        ColumnTextBox.HeaderText = "Name"
        ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
        ColumnTextBox.Width = 100
        Me.myDgv.Columns.Add(ColumnTextBox)

        '*** Column (Email) ***'
        ColumnTextBox = New DataGridViewTextBoxColumn()
        ColumnTextBox.DataPropertyName = "Email"
        ColumnTextBox.HeaderText = "Email"
        ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
        ColumnTextBox.Width = 100
        Me.myDgv.Columns.Add(ColumnTextBox)

        '*** Column (CountryCode) ***'
        ColumnTextBox = New DataGridViewTextBoxColumn()
        ColumnTextBox.DataPropertyName = "CountryCode"
        ColumnTextBox.HeaderText = "CountryCode"
        ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
        ColumnTextBox.Width = 100
        Me.myDgv.Columns.Add(ColumnTextBox)

        '*** Column (Budget) ***'
        ColumnTextBox = New DataGridViewTextBoxColumn()
        ColumnTextBox.DataPropertyName = "Budget"
        ColumnTextBox.HeaderText = "Budget"
        ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
        ColumnTextBox.Width = 100
        Me.myDgv.Columns.Add(ColumnTextBox)

        '*** Column (Used) ***'
        ColumnTextBox = New DataGridViewTextBoxColumn()
        ColumnTextBox.DataPropertyName = "Used"
        ColumnTextBox.HeaderText = "Used"
        ColumnTextBox.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter
        ColumnTextBox.Width = 100
        Me.myDgv.Columns.Add(ColumnTextBox)

    End Sub

    Private Sub ckBox_CheckedChanged()
        Dim i As Integer = 0
        For j As Integer = 0 To Me.myDgv.RowCount - 1
            Me.myDgv(0, j).Value = True
        Next
    End Sub