What are some common methods for displaying hierarchical data from a MySQL database in PHP?

When displaying hierarchical data from a MySQL database in PHP, one common method is to use a recursive function to traverse the tree structure. Another approach is to use nested loops to iterate through parent-child relationships. Additionally, utilizing SQL queries with the "ORDER BY" clause can help organize the data in a hierarchical manner. 

// Recursive function to display hierarchical data
function displayHierarchy($parent_id, $level = 0) {
    $result = mysqli_query($connection, "SELECT * FROM table WHERE parent_id = $parent_id");
    
    while ($row = mysqli_fetch_assoc($result)) {
        echo str_repeat('-', $level) . $row['name'] . "<br>";
        displayHierarchy($row['id'], $level + 1);
    }
}

// Call the function with the root parent_id
displayHierarchy(0);

Keywords

MySQL PHP hierarchical data display methods

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