類別層次結構（PHP / MySQL）

Question

我試圖從層次結構中獲取MySQL數據庫中的所有類別和子類別：

我的結果應該是那樣的（只是示例）：

1. 貓A
   • 子貓1
     • Sub_Sub_Cat 1
     • Sub_Sub_Cat 2
   • Sub_Cat 2
2. 貓B
3. 貓C
4. ...

MySQL代碼：

CREATE TABLE IF NOT EXISTS `categories` (
   `category_id` mediumint(8) unsigned NOT NULL AUTO_INCREMENT,
   `parent_id` mediumint(8) unsigned NOT NULL DEFAULT '0' COMMENT 'for sub-categories'
  PRIMARY KEY (`category_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 ;

簡單地說，如何使用PHP代碼進行hirarchy？

Answer 1

使用鄰接列表模型時，可以一次生成結構。

取自One Pass親子陣列結構（2007年9月;作者Nate Weiner） ：

$refs = array();
$list = array();

$sql = "SELECT item_id, parent_id, name FROM items ORDER BY name";

/** @var $pdo \PDO */
$result = $pdo->query($sql);

foreach ($result as $row)
{
    $ref = & $refs[$row['item_id']];

    $ref['parent_id'] = $row['parent_id'];
    $ref['name']      = $row['name'];

    if ($row['parent_id'] == 0)
    {
        $list[$row['item_id']] = & $ref;
    }
    else
    {
        $refs[$row['parent_id']]['children'][$row['item_id']] = & $ref;
    }
}

從鏈接的文章中，這是一個用於創建輸出列表的代碼段。 它是遞歸的，如果節點有子節點，它會再次調用自己來構建子樹。

function toUL(array $array)
{
    $html = '<ul>' . PHP_EOL;

    foreach ($array as $value)
    {
        $html .= '<li>' . $value['name'];
        if (!empty($value['children']))
        {
            $html .= toUL($value['children']);
        }
        $html .= '</li>' . PHP_EOL;
    }

    $html .= '</ul>' . PHP_EOL;

    return $html;
}

相關問題：

• 如何從對象的數組記錄集中獲取嵌套的HTML列表？

Answer 2

我有一個新想法，我認為它會很好。 這個想法是這樣的：在category_parent列中，我們將插入對該節點的所有父節點的引用。

+----+----------------------+-----------------+
| id | category_name        |    hierarchy    |
+----+----------------------+-----------------+
| 1  | cat1                 |        1        |
+----+----------------------+-----------------+
| 2  | cat2                 |        2        |
+----+----------------------+-----------------+
| 3  | cat3                 |        3        |
+----+----------------------+-----------------+
| 4  | subcat1_1            |       1-4       |
+----+----------------------+-----------------+
| 5  | subcat1_2            |       1-5       |
+----+----------------------+-----------------+
| 6  | subsubcat1_1         |      1-4-6      |
+----+----------------------+-----------------+
| 7  | subsubcat1_2         |      1-4-7      |
+----+----------------------+-----------------+
| 8  | subsubcat1_3         |      1-4-8      |
+----+----------------------+-----------------+
| 9  | subsubcat1_3_1       |     1-4-8-9     |
+----+----------------------+-----------------+
| 10 | subsubcat1_3_2       |     1-4-8-10    |
+----+----------------------+-----------------+
| 11 | subsubcat1_3_1_1     |    1-4-8-9-11   |
+----+----------------------+-----------------+
| 12 | subsubsubcat1_3_1_1  |   1-4-8-9-12    |
+----+----------------------+-----------------+
| 13 | subsubsubcat1_3_1_2  |  1-4-8-9-11-13  |
+----+----------------------+-----------------+
| 14 | subsubsubcat1_2_1_3  |  1-4-8-9-11-14  |
+----+----------------------+-----------------+

如果你查看我更新的表格，你會注意到每條記錄都有一個鏈接到它的父母，不僅是直接的，還有所有的父母。 為了這項工作，我做了一些修改，插入：

Insert into table_name (category_name, hierarchy) values ('new_name', (concat(parent_hierarch, '-', (SELECT Auto_increment FROM information_schema.tables WHERE table_name='table_name'))))

現在讓我們提出您想要的查詢：

1-所有子類別的汽車：

select * from table_name where hierarchy like '1-%'

2-如果你需要BLACK的所有父母，你只需輸入：

select * from table_name where hierarchy = '1-4-8-9' or hierarchy = '1-4-8' or hierarchy = '1-4' or hierarchy = '1'

（您可以從php構建該查詢，在' - 'char處拆分層次結構字段）

3-要查看具有級別和直接父級的所有類別：

select *, SUBSTR(hierarchy, 1, (LENGTH(hierarchy) - LENGTH(id) - 1)) as parent, LENGTH(hierarchy) - LENGTH(REPLACE(hierarchy, '-', '')) as level From table_name

+----+----------------------+-----------------+-----------+--------+
| id | category name        |    hierarchy    |   parent  |  level |
+----+----------------------+-----------------+-----------+--------+
| 1  | cat1                 |        1        |           |    0   |
+----+----------------------+-----------------+-----------+--------+
| 2  | cat2                 |        2        |           |    0   |
+----+----------------------+-----------------+-----------+--------+
| 3  | cat3                 |        3        |           |    0   |
+----+----------------------+-----------------+-----------+--------+
| 4  | subcat1_1            |       1-4       |     1     |    1   |
+----+----------------------+-----------------+-----------+--------+
| 5  | subcat1_2            |       1-5       |     1     |    1   |
+----+----------------------+-----------------+-----------+--------+
| 6  | subsubcat1_1         |      1-4-6      |    1-4    |    2   |
+----+----------------------+-----------------+-----------+--------+
| 7  | subsubcat1_2         |      1-4-7      |    1-4    |    2   |
+----+----------------------+-----------------+-----------+--------+
| 8  | subsubcat1_3         |      1-4-8      |    1-4    |    2   |
+----+----------------------+-----------------+-----------+--------+
| 9  | subsubcat1_3_1       |     1-4-8-9     |   1-4-8   |    3   |
+----+----------------------+-----------------+-----------+--------+
| 10 | subsubcat1_3_2       |     1-4-8-10    |   1-4-8   |    3   |
+----+----------------------+-----------------+-----------+--------+
| 11 | subsubcat1_3_1_1     |    1-4-8-9-11   |  1-4-8-9  |    4   |
+----+----------------------+-----------------+-----------+--------+
| 12 | subsubsubcat1_3_1_1  |   1-4-8-9-12    |  1-4-8-9  |    4   |
+----+----------------------+-----------------+-----------+--------+
| 13 | subsubsubcat1_3_1_2  |  1-4-8-9-11-13  |1-4-8-9-11 |    5   |
+----+----------------------+-----------------+-----------+--------+
| 14 | subsubsubcat1_2_1_3  |  1-4-8-9-11-14  |1-4-8-9-11 |    5   |
+----+----------------------+-----------------+-----------+--------+

這是一個新想法，需要一些改進。

Answer 3

@Amnon您的代碼完美無缺。 剛剛使用CodeIgniter測試它，它就像一個魅力。 如果有人需要，這是工作代碼：

<?php

function disTree($all_cats) {
$tree = array();
foreach ($all_cats as $cat)
{
    $pid  = $cat->parent_id;
    $id   = $cat->cat_id;
    $name = $cat->cat_name;

    // Create or add child information to the parent node
    if (isset($tree[$pid]))
        // a node for the parent exists
        // add another child id to this parent
        $tree[$pid]["children"][] = $id;
    else
        // create the first child to this parent
        $tree[$pid] = array("children"=>array($id));

    // Create or add name information for current node
    if (isset($tree[$id]))
        // a node for the id exists:
        // set the name of current node
        $tree[$id]["name"] = $name;
    else
        // create the current node and give it a name
        $tree[$id] = array( "name"=>$name );
}
return $tree;
}


function toUL($tree, $id, $html){
  $html .= '<ul>'.PHP_EOL;

  if (isset($tree[$id]['name']))
    $html .= '<li>' . $tree[$id]['name'];

  if (isset($tree[$id]['children']))
  {
    $arChildren = &$tree[$id]['children'];
    $len = count($arChildren);
    for ($i=0; $i<$len; $i++) {
        $html .= toUL($tree, $arChildren[$i], "");
    }
    $html .= '</li>'.PHP_EOL;
  }

  $html .= '</ul>'.PHP_EOL;
  return $html;
}

$tree = disTree($all_cats);
// Display the tree
echo toUL($tree, 0, "");

?>

我唯一改變的是添加我自己的數組（$ all_cats）。

Answer 4

請嘗試以下代碼

//連接到mysql並選擇db

$conn = mysqli_connect('localhost', 'user', 'password','database');

if( !empty($conn->connect_errno)) die("Error " . mysqli_error($conn));

//call the recursive function to print category listing
category_tree(0);

//Recursive php function
function category_tree($catid){
global $conn;

$sql = "select * from category where parent_id ='".$catid."'";
$result = $conn->query($sql);

while($row = mysqli_fetch_object($result)):
$i = 0;
if ($i == 0) echo '<ul>';
 echo '<li>' . $row->cat_name;
 category_tree($row->id);
 echo '</li>';
$i++;
 if ($i > 0) echo '</ul>';
endwhile;
}
//close the connection
mysqli_close($conn);
?>

更多...

Answer 5

還有另一種方法可以達到相同的效果，我覺得它更容易理解（沒有參考技巧）。 您通過將相關信息添加到當前節點及其父節點來構建樹（假設foreach迭代SQL查詢中返回的行）：

$tree = array();
foreach ($query->result() as $row)
{
    $pid  = $row->parent_id;
    $id   = $row->id;
    $name = $row->name;

    // Create or add child information to the parent node
    if (isset($tree[$pid]))
        // a node for the parent exists
        // add another child id to this parent
        $tree[$pid]["children"][] = $id;
    else
        // create the first child to this parent
        $tree[$pid] = array("children"=>array($id));

    // Create or add name information for current node
    if (isset($tree[$id]))
        // a node for the id exists:
        // set the name of current node
        $tree[$id]["name"] = $name;
    else
        // create the current node and give it a name
        $tree[$id] = array( "name"=>$name );
}
return $tree;

並顯示樹：

function toUL($tree, $id, $html){
  $html .= '<ul>'.PHP_EOL;

  if (isset($tree[$id]['name']))
    $html .= '<li>' . $tree[$id]['name'];

  if (isset($tree[$id]['children']))
  {
    $arChildren = &$tree[$id]['children'];
    $len = count($arChildren);
    for ($i=0; $i<$len; $i++) {
        $html .= toUL($tree, $arChildren[$i], "");
    }
    $html .= '</li>'.PHP_EOL;
  }

  $html .= '</ul>'.PHP_EOL;
  return $html;
}

// Display the tree
echo toUL($tree, 0, "");