如何在选择列表中显示类别,子类别,子子类别 – php / mysql？

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.首先看看我的数据库表(tb_categories) –

我想要HTML格式的以下输出 –

“无”和“未分类”这两个项目在代码中是硬编码的.我想知道如何使用选择列表选项按层次顺序显示类别及其子类别.

我正在尝试使用以下sql查询,其中我使用自联接.这里是 –

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该选择列表中显示上述数据.我们怎么做？我们怎样才能使用连接呢？如果我们使用连接,那么我们是否需要一些数组来存储和排序结果？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？ 最佳答案 假设您的给定数组在$array中,您可以使用它.但正如我告诉你的那样,你应该选择id来处理具有相同名称的类别,并将它们用作选择框中的选项值：

  $options = get_options($array);
  echo "

  $options = get_options($array);
  echo "