Turn database result into array

Question

I have just made the update/add/delete part for the \"Closure table\" way of organizing query hierarchical data that are shown on page 70 in this slideshare: http://www.slid

Answer 1

Proposed Solution

This following example gives a little more than you ask for, but it's a really nice way of doing it and still demonstrates where the information comes from at each stage.

It uses the following table structure:

+--------+------------------+------+-----+---------+----------------+
| Field  | Type             | Null | Key | Default | Extra          |
+--------+------------------+------+-----+---------+----------------+
| id     | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| parent | int(10) unsigned | NO   |     | NULL    |                |
| name   | varchar(45)      | NO   |     | NULL    |                |
+--------+------------------+------+-----+---------+----------------+

Here it is:

';

    $categories = Category::getTopCategories();
    print_r($categories);

    echo '

'; class Category { /** * The information stored in the database for each category */ public $id; public $parent; public $name; // The child categories public $children; public function __construct() { // Get the child categories when we get this category $this->getChildCategories(); } /** * Get the child categories * @return array */ public function getChildCategories() { if ($this->children) { return $this->children; } return $this->children = self::getCategories("parent = {$this->id}"); } //////////////////////////////////////////////////////////////////////////// /** * The top-level categories (i.e. no parent) * @return array */ public static function getTopCategories() { return self::getCategories('parent = 0'); } /** * Get categories from the database. * @param string $where Conditions for the returned rows to meet * @return array */ public static function getCategories($where = '') { if ($where) $where = " WHERE $where"; $result = mysql_query("SELECT * FROM categories$where"); $categories = array(); while ($category = mysql_fetch_object($result, 'Category')) $categories[] = $category; mysql_free_result($result); return $categories; } }

Test Case

In my database I have the following rows:

+----+--------+-----------------+
| id | parent | name            |
+----+--------+-----------------+
|  1 |      0 | First Top       |
|  2 |      0 | Second Top      |
|  3 |      0 | Third Top       |
|  4 |      1 | First Child     |
|  5 |      1 | Second Child    |
|  6 |      2 | Third Child     |
|  7 |      2 | Fourth Child    |
|  8 |      4 | First Subchild  |
|  9 |      4 | Second Subchild |
+----+--------+-----------------+

And thus the script outputs the following (lengthy) information:

Array
(
    [0] => Category Object
        (
            [id] => 1
            [parent] => 0
            [name] => First Top
            [children] => Array
                (
                    [0] => Category Object
                        (
                            [id] => 4
                            [parent] => 1
                            [name] => First Child
                            [children] => Array
                                (
                                    [0] => Category Object
                                        (
                                            [id] => 8
                                            [parent] => 4
                                            [name] => First Subchild
                                            [children] => Array
                                                (
                                                )

                                        )

                                    [1] => Category Object
                                        (
                                            [id] => 9
                                            [parent] => 4
                                            [name] => Second Subchild
                                            [children] => Array
                                                (
                                                )

                                        )

                                )

                        )

                    [1] => Category Object
                        (
                            [id] => 5
                            [parent] => 1
                            [name] => Second Child
                            [children] => Array
                                (
                                )

                        )

                )

        )

    [1] => Category Object
        (
            [id] => 2
            [parent] => 0
            [name] => Second Top
            [children] => Array
                (
                    [0] => Category Object
                        (
                            [id] => 6
                            [parent] => 2
                            [name] => Third Child
                            [children] => Array
                                (
                                )

                        )

                    [1] => Category Object
                        (
                            [id] => 7
                            [parent] => 2
                            [name] => Fourth Child
                            [children] => Array
                                (
                                )

                        )

                )

        )

    [2] => Category Object
        (
            [id] => 3
            [parent] => 0
            [name] => Third Top
            [children] => Array
                (
                )

        )

)

Example Usage

I'd suggest creating some kind of recursive function if you're going to create menus from the data:

function outputCategories($categories, $startingLevel = 0)
{
    $indent = str_repeat("    ", $startingLevel);

    foreach ($categories as $category)
    {
        echo "$indent{$category->name}\n";
        if (count($category->children) > 0)
            outputCategories($category->children, $startingLevel+1);
    }
}

$categories = Category::getTopCategories();
outputCategories($categories);

which would output the following:

First Top
    First Child
        First Subchild
        Second Subchild
    Second Child
Second Top
    Third Child
    Fourth Child
Third Top

Enjoy