public int checklogin(string mand, string password) { AccessData acc = new AccessData(); SqlDataReader reader = acc.ExecuteReader("SELECT maND, MatKhau FROM NGUOIDUNG"); while (reader.Read()) { if (reader[0].ToString() == mand && reader[1].ToString() == password) { //reader[0] tương ứng cho textbox username //reader[1] tương ứng cho textbox password return(1); } } return(0); }