如何在选择列表中显示类别，子类别，子子类别-php/mysql?

问题描述

我想在选择列表(下拉列表)中显示类别，子类别和子子类别，就像WordPress在其管理面板中显示的方式一样.首先看一下我的数据库表(tb_categories)-

I want to display categories, subcategories and sub-subcategories in a select list (drop-down list) like the way the WordPress shows in its admin panel. First look at my database table (tb_categories) -

我想要以下HTML格式的输出-

I want the following output in HTML form -

这两个项目无"和未分类"在代码中进行了硬编码.我想知道如何使用选择列表选项按层次结构显示类别及其子类别.

The two items "None" and "Uncategorized" are hardcoded in the code. I am wondering how to display categories and their subcategories in hierarchical order using select list options.

我正在尝试使用自我连接的以下SQL查询.这是-

I am trying with the following sql query in which I am using self join. Here it is -

SELECT
    `cat`.`category_name` AS 'category name',
    `cat2`.`category_name` AS 'parent category'
FROM
    `tb_categories` AS `cat`
LEFT JOIN `tb_categories` AS `cat2` ON `cat`.`category_parent` = `cat2`.`category_id`
ORDER BY
    'parent category'

它给出的输出是-

Array
(
    [0] => Array
        (
            [0] => My Parent Category
            [category name] => My Parent Category
            [1] =>
            [parent category] =>
        )

    [1] => Array
        (
            [0] => Parent Category 2
            [category name] => Parent Category 2
            [1] =>
            [parent category] =>
        )

    [2] => Array
        (
            [0] => Parent Category 3
            [category name] => Parent Category 3
            [1] =>
            [parent category] =>
        )

    [3] => Array
        (
            [0] => My Child Category
            [category name] => My Child Category
            [1] => My Parent Category
            [parent category] => My Parent Category
        )

    [4] => Array
        (
            [0] => Sports
            [category name] => Sports
            [1] =>
            [parent category] =>
        )

    [5] => Array
        (
            [0] => Cricket is best
            [category name] => Cricket is best
            [1] => Sports
            [parent category] => Sports
        )

    [6] => Array
        (
            [0] => AJAX
            [category name] => AJAX
            [1] =>
            [parent category] =>
        )

    [7] => Array
        (
            [0] => hockey is best
            [category name] => hockey is best
            [1] => Sports
            [parent category] => Sports
        )

)

我不知道，甚至不确定如何在选择列表中显示以上数据.我们该怎么做?我们如何使用联接做到这一点?如果我们使用联接，那么是否需要一些数组来存储结果并对其进行排序?还有，我们如何在循环中使用多个查询来做到这一点?哪种方法最好?

I don't know and even not sure how can I display above data in that select list. How we do that? How can we do it using joins? If we use joins then do we need some array to store and sort the results? And also how do we do it using several queries in a loop? Which method will be best?

推荐答案

假定给定数组位于$ array中，则可以使用此数组.但是，正如我已经告诉您的那样，您应该选择ID以处理具有相同名称的类别，并将其用作选择框中的选项值:

Assuming your given array is in $array you can use this. But as I told you already you should select the ids to handle categories with the same name and to use them as option values in your selectbox:

  $options = get_options($array);
  echo "<select>";
  foreach($options as $val) {
    echo "<option>".$val."</option>";
  }
  echo "</select>";

  function get_options($array, $parent="", $indent="") {
    $return = array();
    foreach($array as $key => $val) {
      if($val["parent category"] == $parent) {
        $return[] = $indent.$val["category name"];
        $return = array_merge($return, get_options($array, $val["category name"], $indent."&nbsp;&nbsp;&nbsp;"));
      }
    }
    return $return;
  }

---

假设您现在数组中的ID为"category_id"和"parent_category_id"，则可以使用它. $ return键之前的"x"只是为了避免php更改您的键，因为它们是数字.

---

Assuming that you now have the ids in your array as "category_id" and "parent_category_id" you can use this. The "x" prior to the key in $return is just to avoid that php changes your keys, because they are numeric.

  $options = get_options($array);
  echo "<select>";
  foreach($options as $key => $val) {
    echo "<option value='".substr($key,1)."'>".$val."</option>";
  }
  echo "</select>";

  function get_options($array, $parent=0, $indent="") {
    $return = array();
    foreach($array as $key => $val) {
      if($val["parent_category_id"] == $parent) {
        $return["x".$val["category_id"]] = $indent.$val["category name"];
        $return = array_merge($return, get_options($array, $val["category_id"], $indent."&nbsp;&nbsp;&nbsp;"));
      }
    }
    return $return;
  }

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