private void dt_student_SelectionChanged(object sender, EventArgs e) { if (dt_student.SelectedRows.Count > 0) { btnAdd_student.Visible = false; DataGridViewRow row = dt_student.SelectedRows[0]; Student_User_Account = row.Cells[0].Value.ToString(); txtUser_name_student.Text = row.Cells[0].Value.ToString(); txtCMND_TCC_student.Text = row.Cells[5].Value.ToString(); txtFull_name_student.Text = row.Cells[4].Value.ToString(); txtMail_student.Text = row.Cells[8].Value.ToString(); txtSDT_student.Text = row.Cells[7].Value.ToString(); dtStudent_Picker.Value = DateTime.Parse(row.Cells[6].Value.ToString()); Class_CBB.Text = BUS_Admin.findClassByID(row.Cells[3].Value.ToString()); } }