在PHP中构建动态菜单时，MySQL中的数据不显示

我正在使用PHP和MySQL构建一个动态菜单，但结果没有显示：

网站结构如下所示：

<div id="container">
        <ul class="nav">
            <li><a href="index.php">home</a></li>                 
            <li>
                <a href="#" id="destinations">destinations &triangledown;</a>

                <div id="subMenu">   

                <div class="nav-column">                         
                    <a href="#" class="continente">Europe</a>                           
                </div>

                <div class="nav-column" >                       
                    <a href="#" id="Africa">Africa</a>                         
                </div>      

                <div class="nav-column" >                      
                    <a href="#" id="Asia">Asia</a>                          
                </div>   

                 <div class="nav-column">                      
                     <a href="#" id="Oceania">Oceania</a>                          
                </div> 

                 <div class="nav-column">                      
                     <a href="#" id="North">North America</a>                          
                </div>   

                <div class="nav-column">                      
                    <a href="#" id="South">South America</a>                          
                </div>                    
                </div>                    
            </li>                
            <li><a href="#about">about</a></li>
            <li><a href="#contact">contact</a></li>
        </ul>         
</div> 

---

您没有关闭echo中的

。如果在

id='cnt'

之后添加一个

，它是否有效？你是对的。现在显示子菜单。现在，我仍然无法显示包含国家的子菜单。我试图显示一个包含相应国家/地区列表的div，但它仍然不显示。我已经编辑了代码并添加了jQuery代码。

<?php
    error_reporting(E_ALL);
    ini_set('display_errors', 1);
?>

<div id="container">
     <ul class="nav">
         <li><a href="index.php">home</a></li>                 
         <li><a href="#" id="destinations">destinations</a>
             <div id="subMenu">                   
             <?php 
                $servername = "localhost:3306";
                $username = "root";
                $password = "";
                $dbname = "site_comboios";

               //Open DB connection
      $mysqli = new mysqli($servername, $username, $password, $dbname);

     //check connection
     if($mysqli->connect_errno) {
     echo 'Error connecting to database';
     exit();
           }

     //show sub-menu
     $query = "SELECT * FROM continentes ORDER BY id";
     $result = mysqli_query($mysqli, $query);  
     $div = 0;    
     while ($row = mysqli_fetch_assoc($result)) {
          $país = $row['continente'];
          echo "<div class='nav-column'><a href='#' class='continente'  data-id='cnt_submenu'>" .($país). "</a></div> ";  </div> ";
        }
     ?>                      

</div>                    
</li>                
<li><a href="#about">about</a></li>
<li><a href="#contact">contact</a></li>
        </ul>         
 </div>  


<div id="cnt_submenu_"   class="submenu_continente active">    

<?php
    //retrieve european countries from DB and open <ul> with 9 results
    $conn = mysqli_connect("localhost:3306","root","","site_comboios");
    $sql_countries = "SELECT * FROM countries ORDER BY id WHERE      id_continentes = 1" ;
    $res_countries = mysqli_query($conn, $sql_countries);

if($res_countries > 0) { 
     while ($row_countries = mysqli_fetch_assoc($res_countries)) {
        $país = $row_countries['id_continente'];
        echo "<ul><li><a href='#'>". $país ."";
}

} else if ($res_countries == 9) {
       echo '</li></ul>';
}
?>
<span class="close">x</span>
</div>

//Open and close each div with country list 
$('.continente').hover(function(){ 
      menuHide('submenu_continente' . $(this).data("id")  );
$('#cnt_submenu_' . $(this).data("id") ).show(); 
      },function(){
$('#cnt_submenu_' . $(this).data("id")).mouseleave( function() {
      $(this).hide();    
      });
});