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PHP recursively implements infinite classification tree

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Release： 2023-03-05 22:48:02

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The infinite level tree diagram can be said to be a distinctive feature of the infinite level column. Let’s take a look at two different writing methods.

1. Database design

CREATE TABLE `bg_cate` (
`cate_Id` int(30) unsigned NOT NULL AUTO_INCREMENT,
`cate_ParentId` int(30) unsigned DEFAULT &#39;0&#39;,
`cate_Name` varchar(100) NOT NULL,
`cate_Intro` varchar(500) DEFAULT NULL,
`cate_Order` int(30) unsigned DEFAULT &#39;0&#39;,
`cate_Icon` varchar(100) DEFAULT NULL,
PRIMARY KEY (`cate_Id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=34 ;
--
-- 导出表中的数据 `bg_cate`
--
INSERT INTO `bg_cate` (`cate_Id`, `cate_ParentId`, `cate_Name`, `cate_Intro`, `cate_Order`, `cate_Icon`) VALUES
(4, 0, &#39;往事如风&#39;, &#39;记录往事&#39;, 0, &#39;icons/6.gif&#39;),
(5, 0, &#39;水煮三国&#39;, &#39;品位三国智慧&#39;, 0, &#39;icons/3.gif&#39;),
(2, 0, &#39;技术学习&#39;, &#39;平时学习的一些笔记，欢迎批评指正。&#39;, 0, &#39;icons/18.gif&#39;),
(3, 0, &#39;生活点滴&#39;, &#39;记录生活点滴&#39;, 0, &#39;icons/2.gif&#39;),
(6, 0, &#39;栀子花开&#39;, &#39;青春无限&#39;, 0, &#39;icons/8.gif&#39;),
(7, 0, &#39;假日休闲&#39;, &#39;悠闲、自在&#39;, 0, &#39;icons/24.gif&#39;),
(8, 2, &#39;html&#39;, &#39;html学习&#39;, 0, &#39;icons/1.gif&#39;),
(9, 2, &#39;css&#39;, &#39;css学习&#39;, 0, &#39;icons/1.gif&#39;),
(10, 2, &#39;php&#39;, &#39;php学习&#39;, 0, &#39;icons/18.gif&#39;),
(11, 10, &#39;php基础知识&#39;, &#39;php基础知识&#39;, 0, &#39;icons/1.gif&#39;),
(12, 10, &#39;oop&#39;, &#39;oop&#39;, 0, &#39;icons/1.gif&#39;),
(13, 10, &#39;php安全&#39;, &#39;讲述php安全&#39;, 0, &#39;icons/1.gif&#39;),
(14, 10, &#39;seagull framework&#39;, &#39;seagull framework&#39;, 0, &#39;icons/1.gif&#39;),
(15, 2, &#39;javascript&#39;, &#39;javascript学习&#39;, 0, &#39;icons/1.gif&#39;),
(16, 2, &#39;设计模式&#39;, NULL, 0, &#39;icons/1.gif&#39;),
(17, 2, &#39;软件工程&#39;, &#39;软件工程学习&#39;, 0, &#39;icons/1.gif&#39;),
(18, 3, &#39;厦门生活&#39;, &#39;厦门生活&#39;, 0, &#39;icons/8.gif&#39;),
(19, 3, &#39;大学生活&#39;, &#39;大学生活&#39;, 0, &#39;icons/8.gif&#39;),
(20, 3, &#39;童年生活&#39;, &#39;童年生活&#39;, 0, &#39;icons/15.gif&#39;),
(21, 19, &#39;学习&#39;, &#39;学习&#39;, 0, &#39;icons/1.gif&#39;),
(22, 19, &#39;运动&#39;, &#39;运动&#39;, 0, &#39;icons/16.gif&#39;),
(23, 19, &#39;旅游&#39;, &#39;旅游&#39;, 0, &#39;icons/24.gif&#39;),
(24, 22, &#39;排球&#39;, &#39;排球&#39;, 0, &#39;icons/9.gif&#39;),
(25, 22, &#39;篮球&#39;, &#39;篮球&#39;, 0, &#39;icons/9.gif&#39;),
(26, 22, &#39;羽毛球&#39;, &#39;羽毛球&#39;, 0, &#39;icons/9.gif&#39;),
(27, 22, &#39;乒乓球&#39;, &#39;乒乓球&#39;, 0, &#39;icons/9.gif&#39;);

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2. Get the data from the database and put it into the array.

require_once &#39;./classes/MyDB.php&#39;;
$con = MyDB::singleton();
$sql = <<<SQL
   select * from bg_cate cate
SQL;
$data = $con->getAll($sql);
//print_r($data);

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I use the pear class library for database operations.
The data format of the final $data is as follows:

Array
(
   [0] => Array
       (
           [cate_Id] => 4
           [cate_ParentId] => 0
           [cate_Name] => 往事如风
           [cate_Intro] => 记录往事
           [cate_Order] => 0
           [cate_Icon] => icons/6.gif
       )
   [1] => Array
       (
           [cate_Id] => 5
           [cate_ParentId] => 0
           [cate_Name] => 水煮三国
           [cate_Intro] => 品位三国智慧
           [cate_Order] => 0
           [cate_Icon] => icons/3.gif
       )

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3. Convert the data from the previous step into a tree-shaped array
The code is as follows:

function getTree($data, $pId)
{
$tree = &#39;&#39;;
foreach($data as $k => $v)
{
  if($v[&#39;cate_ParentId&#39;] == $pId)
  {        //父亲找到儿子
   $v[&#39;cate_ParentId&#39;] = getTree($data, $v[&#39;cate_Id&#39;]);
   $tree[] = $v;
   //unset($data[$k]);
  }
}
return $tree;
}
$tree = getTree($data, 0);

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The final output data format of $tree is:

Array
(
   [0] => Array
       (
           [cate_Id] => 4
           [cate_ParentId] =>
           [cate_Name] => 往事如风
           [cate_Intro] => 记录往事
           [cate_Order] => 0
           [cate_Icon] => icons/6.gif
       )
   [1] => Array
       (
           [cate_Id] => 5
           [cate_ParentId] =>
           [cate_Name] => 水煮三国
           [cate_Intro] => 品位三国智慧
           [cate_Order] => 0
           [cate_Icon] => icons/3.gif
       )
   [2] => Array
       (
           [cate_Id] => 2
           [cate_ParentId] => Array
               (
                   [0] => Array
                       (
                           [cate_Id] => 8
                           [cate_ParentId] =>
                           [cate_Name] => html
                           [cate_Intro] => html学习
                           [cate_Order] => 0
                           [cate_Icon] => icons/1.gif
                       )

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4. Convert the tree array to html
The code is as follows:

function procHtml($tree)
{
$html = &#39;&#39;;
foreach($tree as $t)
{
  if($t[&#39;cate_ParentId&#39;] == &#39;&#39;)
  {
   $html .= "<li>{$t[&#39;cate_Name&#39;]}</li>";
  }
  else
  {
   $html .= "<li>".$t[&#39;cate_Name&#39;];
   $html .= procHtml($t[&#39;cate_ParentId&#39;]);
   $html = $html."</li>";
  }
}
return $html ? &#39;<ul>&#39;.$html.&#39;</ul>&#39; : $html ;
}
echo procHtml($tree);

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The code format of the output html is:

<ul>
<li>往事如风</li>
<li>水煮三国</li>
<li>技术学习
  <ul>
   <li>html</li>
   <li>css</li>
   <li>php
    <ul>
     <li>php基础知识</li>
     <li>oop</li>
     <li>php安全</li>

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5. Code integration

function getTree($data, $pId)
{
$html = &#39;&#39;;
foreach($data as $k => $v)
{
  if($v[&#39;cate_ParentId&#39;] == $pId)
  {        //父亲找到儿子
   $html .= "<li>".$v[&#39;cate_Name&#39;];
   $html .= getTree($data, $v[&#39;cate_Id&#39;]);
   $html = $html."</li>";
  }
}
return $html ? &#39;<ul>&#39;.$html.&#39;</ul>&#39; : $html ;
}
echo getTree($data, 0);

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6. Add CSS styles

PHP recursively implements infinite classification tree

##The second one is seen from open source websites, very very Introduction.

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It can be seen that the second code only uses 5 lines of code to achieve an infinite classification tree, which is very worthy of everyone's reference and learning.

If you want to know more about PHP, please continue to pay attention to the PHP Chinese website

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