public String soMui(String tenBenh) {
//        String ketQua = "";
//        try {
//            Class.forName("com.mysql.jdbc.Driver").newInstance();
//            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/baitap?"
//                    + "user=root&password=123456");
//
//            String sql = "select MaBenh from benh where TenBenh = '" + tenBenh + "'";
//            PreparedStatement ps = conn.prepareStatement(sql);
//
//            ResultSet rs = ps.executeQuery();
//            String MaBenh = "";
//            while (rs.next()) {
//                MaBenh = rs.getString("MaBenh");
//            }
//
//            if (!"".equals(MaBenh)) {
//                sql = "select TenVacxin, SoMui from (vacxin, phongbenh) where vacxin.MaVacxin = phongbenh.MaVacxin and phongbenh.MaBenh = '" + MaBenh + "'";
//                ps = conn.prepareStatement(sql);
//                rs = ps.executeQuery();
//
//                while (rs.next()) {
//                    ketQua += rs.getString("TenVacxin") + ": " + rs.getInt("SoMui") +"\n";
//                }
//            } else {
//                ketQua = "Khong tim thay";
//            }
//
//        } catch (ClassNotFoundException ex) {
//            Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
//        } catch (SQLException ex) {
//            Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
//        } catch (InstantiationException ex) {
//            Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
//        } catch (IllegalAccessException ex) {
//            Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex);
//        }
//        return ketQua;
//    }