PHP में नेस्टेड फ़ंक्शन का उपयोग करके चयनित श्रेणी से उपश्रेणियों का चयन कैसे करें?

एक दो समाधान हैं। सबसे पहले, मैं निम्नलिखित डेटा का उपयोग करूंगा (categories तालिका) एक उदाहरण के रूप में।

+----+--------------------------+-----------+
| id | name                     | parent_id |
+----+--------------------------+-----------+
|  1 | Electronics              |      NULL |
|  2 | Apparel & Clothing       |      NULL |
|  3 | Phones & Accessories     |         1 |
|  4 | Computer & Office        |         1 |
|  5 | Men's Clothing           |         2 |
|  6 | Women's Clothing         |         2 |
|  7 | Cell Phones              |         3 |
|  8 | Cell Phone Accessories   |         3 |
|  9 | Phone Parts              |         3 |
| 10 | Computers & Accessories  |         4 |
| 11 | Tablets & Accessories    |         4 |
| 12 | Computer Peripherals     |         4 |
| 13 | Computer Components      |         4 |
| 14 | Office Electronics       |         4 |
+----+--------------------------+-----------+

समाधान 1 (आसन्न सूची ):

आप साथ (सामान्य तालिका भाव) खंड (MySQL 8.0 की आवश्यकता है):

// Database connection

$options = [
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
    PDO::ATTR_EMULATE_PREPARES => false,
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
];

$pdo = new PDO('mysql:host=localhost;dbname=<DATABASE_NAME>', '<USERNAME>', '<PASSWORD>', $options);

function getCategories(PDO $db, $parentId = null)
{
    $sql = $parentId ? 'WITH RECURSIVE cte (id, name, parent_id) AS (SELECT id, name, parent_id FROM categories WHERE parent_id = ? UNION ALL SELECT c.id, c.name, c.parent_id FROM categories c INNER JOIN cte ON c.parent_id = cte.id) SELECT * FROM cte' : 'SELECT * FROM categories';
    $stmt = $db->prepare($sql);
    $stmt->execute($parentId ? [$parentId] : null);
    return $stmt->fetchAll();
}

यदि आप MySQL 5.7 का उपयोग कर रहे हैं, तो उस फ़ंक्शन को इस प्रकार बदलें:

function getCategories(PDO $db, $parentId = null)
{
    $sql = $parentId ? 'SELECT id, name, parent_id FROM (SELECT * FROM categories ORDER BY parent_id, id) c, (select @pv := ?) initialisation WHERE find_in_set(parent_id, @pv) AND LENGTH(@pv := concat(@pv, ",", id))' : 'SELECT * FROM categories';
    $stmt = $db->prepare($sql);
    $stmt->execute($parentId ? [$parentId] : null);
    return $stmt->fetchAll();
}

अपने डेटाबेस में सभी श्रेणियां प्राप्त करने के लिए:

$allCategories = getCategories($pdo);

आउटपुट:

+----+--------------------------+-----------+
| id | name                     | parent_id |
+----+--------------------------+-----------+
|  1 | Electronics              |      NULL |
|  2 | Apparel & Clothing       |      NULL |
|  3 | Phones & Accessories     |         1 |
|  4 | Computer & Office        |         1 |
|  5 | Men's Clothing           |         2 |
|  6 | Women's Clothing         |         2 |
|  7 | Cell Phones              |         3 |
|  8 | Cell Phone Accessories   |         3 |
|  9 | Phone Parts              |         3 |
| 10 | Computers & Accessories  |         4 |
| 11 | Tablets & Accessories    |         4 |
| 12 | Computer Peripherals     |         4 |
| 13 | Computer Components      |         4 |
| 14 | Office Electronics       |         4 |
+----+--------------------------+-----------+

किसी श्रेणी की उपश्रेणियाँ प्राप्त करने के लिए:

$subCategories = getCategories($pdo, 1); // 1 is parent_id

आउटपुट:

+----+--------------------------+-----------+
| id | name                     | parent_id |
+----+--------------------------+-----------+
|  3 | Phones & Accessories     |         1 |
|  4 | Computer & Office        |         1 |
|  7 | Cell Phones              |         3 |
|  8 | Cell Phone Accessories   |         3 |
|  9 | Phone Parts              |         3 |
| 10 | Computers & Accessories  |         4 |
| 11 | Tablets & Accessories    |         4 |
| 12 | Computer Peripherals     |         4 |
| 13 | Computer Components      |         4 |
| 14 | Office Electronics       |         4 |
+----+--------------------------+-----------+

यदि आप एक HTML आउटपुट चाहते हैं, तो आप $allCategories . के माध्यम से लूप कर सकते हैं / $subCategories (आपके उदाहरण के आधार पर):

function prepareCategories(array $categories)
{
    $result = [
        'all_categories' => [],
        'parent_categories' => []
    ];
    foreach ($categories as $category) {
        $result['all_categories'][$category['id']] = $category;
        $result['parent_categories'][$category['parent_id']][] = $category['id'];
    }
    return $result;
}

function buildCategories($categories, $parentId = null)
{
    if (!isset($categories['parent_categories'][$parentId])) {
        return '';
    }

    $html = '<ul>';
    foreach ($categories['parent_categories'][$parentId] as $cat_id) {
        if (isset($categories['parent_categories'][$cat_id])) {
            $html .= "<li><a href='#'>{$categories['all_categories'][$cat_id]['name']}</a>";
            $html .= buildCategories($categories, $cat_id);
            $html .= '</li>';
        } else {
            $html .= "<li><a href='#'>{$categories['all_categories'][$cat_id]['name']}</a></li>";
        }
    }
    $html .= '</ul>';

    return $html;
}

echo buildCategories(prepareCategories($allCategories));

आउटपुट:

echo buildCategories(prepareCategories($subCategories), 1);

आउटपुट:

समाधान 2 (नेस्टेड सेट ):

हम अतिरिक्त कॉलम जोड़ेंगे left और right हमारी तालिका में और उसमें संख्याएँ डालें जो माता-पिता से संबंधित समूहों की पहचान करेंगी। (ध्यान दें कि हम parent_id . का उपयोग नहीं करेंगे कॉलम।)

+----+--------------------------+--------------------------+
| id | name                     | parent_id | left | right |
+----+--------------------------+--------------------------+
|  1 | Electronics              |      NULL |    1 |    22 |
|  2 | Apparel & Clothing       |      NULL |   23 |    28 |
|  3 | Phones & Accessories     |         1 |    2 |     9 |
|  4 | Computer & Office        |         1 |   10 |    21 |
|  5 | Men's Clothing           |         2 |   24 |    25 |
|  6 | Women's Clothing         |         2 |   26 |    27 |
|  7 | Cell Phones              |         3 |    3 |     4 |
|  8 | Cell Phone Accessories   |         3 |    5 |     6 |
|  9 | Phone Parts              |         3 |    7 |     8 |
| 10 | Computers & Accessories  |         4 |   11 |    12 |
| 11 | Tablets & Accessories    |         4 |   13 |    14 |
| 12 | Computer Peripherals     |         4 |   15 |    16 |
| 13 | Computer Components      |         4 |   17 |    18 |
| 14 | Office Electronics       |         4 |   19 |    20 |
+----+--------------------------+--------------------------+

अब, हमें अपना कार्य बदलने की जरूरत है:

function getCategories(PDO $db, $parentId = null)
{
    $sql = $parentId ? 'SELECT children.* FROM categories parent INNER JOIN categories children ON parent.left < children.left AND parent.right > children.left WHERE parent.id = ?' : 'SELECT * FROM categories';
    $stmt = $db->prepare($sql);
    $stmt->execute($parentId ? [$parentId] : null);
    return $stmt->fetchAll();
}

अपने डेटाबेस में सभी श्रेणियां प्राप्त करने के लिए:

$allCategories = getCategories($pdo);

आउटपुट:

+----+--------------------------+--------------------------+
| id | name                     | parent_id | left | right |
+----+--------------------------+--------------------------+
|  1 | Electronics              |      NULL |    1 |    22 |
|  2 | Apparel & Clothing       |      NULL |   23 |    28 |
|  3 | Phones & Accessories     |         1 |    2 |     9 |
|  4 | Computer & Office        |         1 |   10 |    21 |
|  5 | Men's Clothing           |         2 |   24 |    25 |
|  6 | Women's Clothing         |         2 |   26 |    27 |
|  7 | Cell Phones              |         3 |    3 |     4 |
|  8 | Cell Phone Accessories   |         3 |    5 |     6 |
|  9 | Phone Parts              |         3 |    7 |     8 |
| 10 | Computers & Accessories  |         4 |   11 |    12 |
| 11 | Tablets & Accessories    |         4 |   13 |    14 |
| 12 | Computer Peripherals     |         4 |   15 |    16 |
| 13 | Computer Components      |         4 |   17 |    18 |
| 14 | Office Electronics       |         4 |   19 |    20 |
+----+--------------------------+--------------------------+

किसी श्रेणी की उपश्रेणियाँ प्राप्त करने के लिए:

$subCategories = getCategories($pdo, 1); // 1 is parent_id

आउटपुट:

+----+--------------------------+--------------------------+
| id | name                     | parent_id | left | right |
+----+--------------------------+--------------------------+
|  3 | Phones & Accessories     |         1 |    2 |     9 |
|  4 | Computer & Office        |         1 |   10 |    21 |
|  7 | Cell Phones              |         3 |    3 |     4 |
|  8 | Cell Phone Accessories   |         3 |    5 |     6 |
|  9 | Phone Parts              |         3 |    7 |     8 |
| 10 | Computers & Accessories  |         4 |   11 |    12 |
| 11 | Tablets & Accessories    |         4 |   13 |    14 |
| 12 | Computer Peripherals     |         4 |   15 |    16 |
| 13 | Computer Components      |         4 |   17 |    18 |
| 14 | Office Electronics       |         4 |   19 |    20 |
+----+--------------------------+--------------------------+

आप HTML को समाधान 1 . में दिखाए अनुसार रेंडर कर सकते हैं . और पढ़ें नेस्टेड सेट मॉडल में नया डेटा अपडेट करने और डालने के बारे में।

स्रोत और पढ़ें: