在 PHP 和 MYSQLi 中以树结构显示类别和子类别

Question

我试图在树结构中显示类别和子类别，就好像我单击类别然后我可以获得与该类别关联的多个子类别。

我知道这个问题被问过多次，但我发现之前问的所有问题的答案都不清楚。

我创建了一个 table AS :

category : cat_id  , catName
subcategory : id , cat_id , subCatName

我想显示所有类别，当用户单击类别时，应该会列出子类别。

请帮我找到这个查询。提前致谢。

Answer 1

<?php
  $db = new mysqli('localhost','user','password','dbname');
  $query = "SELECT id,cat FROM category";
  $result = $db->query($query);

  while($row = $result->fetch_assoc()){
    $categories[] = array("id" => $row['cat_id'], "val" => $row['cat']);
  }

  $query = "SELECT id, cat_id, subcat FROM subcategory";
  $result = $db->query($query);

  while($row = $result->fetch_assoc()){
    $subcategories[$row['cat_id']][] = array("id" => $row['id'], "val" => $row['subcat']);
  }

  $jsonCats = json_encode($categories);
  $jsonSubCats = json_encode($subcategories);


?>

<!docytpe html>
<html>

  <head>
    <script type='text/javascript'>
      <?php
        echo "var categories = $jsonCats; \n";
        echo "var subcategories = $jsonSubCats; \n";
      ?>
      function loadCategories(){
        var select = document.getElementById("categoriesSelect");
        select.onchange = updateSubCats;
        for(var i = 0; i < categories.length; i++){
          select.options[i] = new Option(categories[i].val,categories[i].id);          
        }
      }
      function updateSubCats(){
        var catSelect = this;
        var catid = this.value;
        var subcatSelect = document.getElementById("subcatsSelect");
        subcatSelect.options.length = 0; //delete all options if any present
        for(var i = 0; i < subcats[catid].length; i++){
          subcatSelect.options[i] = new Option(subcats[catid][i].val,subcategories[catid][i].id);
        }
      }
    </script>

  </head>

  <body onload='loadCategories()'>
    <select id='categoriesSelect'>
    </select>

    <select id='subcatsSelect'>
    </select>
  </body>
</html>

这是您要找的吗？不采用树结构，但您可以轻松更改下拉菜单。

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