private void button4_Click_1(object sender, EventArgs e)
 {
     Deadlines deadlines = new Deadlines(SQL);
     deadlines.Add(dateTimePicker1.Value);
     Deadline deadline = deadlines.GetLast();
     Status = "Naskladňuji...";
     foreach (DataGridViewRow row in dataGridView1.Rows) {
         int id = 0;
         if ((row.Cells["IDColumn"].Value != null) && (int.TryParse(row.Cells["IDColumn"].Value.ToString(), out id) == true)) {
             Transfer item = Transfers.GetRecord(id);
             item.Deadline = deadline;
             Transfers.Change(item);
         }
     }
     Status = "....";
     dataGridView1.Enabled = false;
     button4.Enabled = false;
 }