What are some common pitfalls to avoid when using PHP to populate dropdown menus with data from a database in a hierarchical structure?

One common pitfall to avoid when populating dropdown menus with hierarchical data from a database in PHP is not properly handling the hierarchical structure of the data. To solve this issue, you can use recursive functions to loop through the hierarchical data and generate nested dropdown options accordingly. 

// Function to recursively generate nested dropdown options
function generateDropdownOptions($data, $parent_id = 0, $level = 0) {
    foreach ($data as $row) {
        if ($row['parent_id'] == $parent_id) {
            echo '<option value="' . $row['id'] . '">' . str_repeat('-', $level) . $row['name'] . '</option>';
            generateDropdownOptions($data, $row['id'], $level + 1);
        }
    }
}

// Fetch hierarchical data from the database
$data = $pdo->query("SELECT * FROM categories")->fetchAll(PDO::FETCH_ASSOC);

// Generate dropdown options
generateDropdownOptions($data);

Keywords

SQL injection recursive function PDO prepared statements data sanitization

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