สอบถามปัญหาเกี่ยวกับ Checkbox ใน Datagridview ว่า จะให้ี update ข้อมูลเฉพาะที่เราเลือกเท่านั้น

                foreach (DataGridViewRow Dgvr in dataGridView1.Rows)
                {
if (dataGridRow.Cells["checkbox_col"].Value != null &&
        (bool)dataGridRow.Cells["checkbox_col"].Value) {
         // item is checked
   } else if (dataGridRow.Cells["checkbox_col"].Value == null) {
         // item is null
   }
                }

 Sub TestCal()
        'Dim chk As DataGridViewCheckBoxCell = DirectCast(row.Cells(8), DataGridViewCheckBoxCell)
        Dim i As Integer = 0
        Dim chk As New CheckBox '= grdShowItem.Rows(i).Cells(8)

        Try
            Dim sumSec As Double
            For Each r As DataGridViewRow In Me.grdShowItem.Rows
                ' If grdShowItem.Rows(i).Cells(8).Value IsNot Nothing Then
                If CBool(grdShowItem.Rows(i).Cells(8).Value) = True Then
                    'If chk.Checked = True Then
                    sumSec = r.Cells(2).Value * 3
                    r.Cells(3).Value = sumSec
                End If
            Next
        Catch exsql As SqlException
            MsgBox(exsql.Message, MsgBoxStyle.Exclamation)
        Catch ex As Exception
            MsgBox(ex.Message, MsgBoxStyle.Exclamation)
        End Try

    End Sub