private void FormRegister_Load(object sender, EventArgs e) { PermissionCheck newCheck = new PermissionCheck(); DataTable newtable = new DataTable(); newtable = newCheck.selectReservePatients(); int sum = newtable.Rows.Count; for (int i = 0; i < sum; i++) { comboBox1.Items.Add(newtable.Rows[i][0]); } }