how to draw a tree structure in php from mysql data?

Function for making an array for child-parent:

function parseTree($tree, $root = null) {
    $return = array();
    # Traverse the tree and search for direct children of the root
    foreach($tree as $child => $parent) {
        # A direct child is found
        if($parent == $root) {
            # Remove item from tree (we don't need to traverse this again)
            unset($tree[$child]);
            # Append the child into result array and parse its children
            $return[] = array(
                'name' => $child,
                'children' => parseTree($tree, $child)
            );
        }
    }
    return empty($return) ? null : $return;    
}

For output:

function printtree($tree) {
    if(!is_null($tree) && count($tree) > 0) {
        echo '<ul>';
        foreach($tree as $node) {
            echo '<li>'.$node['name'];
            printTree($node['children']);
            echo '</li>';
        }
        echo '</ul>';
    }
}

Full PHP script:

<?php
$arr = array(
'216'=>103,
'217'=>216,
'88'=>216,
'102'=>NULL,
'103'=>102,
'104'=>102
);
function parseTree($tree, $root = null) {
    $return = array();
    # Traverse the tree and search for direct children of the root
    foreach($tree as $child => $parent) {
        # A direct child is found
        if($parent == $root) {
            # Remove item from tree (we don't need to traverse this again)
            unset($tree[$child]);
            # Append the child into result array and parse its children
            $return[] = array(
                'name' => $child,
                'children' => parseTree($tree, $child)
            );
        }
    }
    return empty($return) ? null : $return;    
}

function printtree($tree) {
    if(!is_null($tree) && count($tree) > 0) {
        echo '<ul>';
        foreach($tree as $b) {
            echo '<li>'.$b['name'];
            printtree($b['children']);
            echo '</li>';
        }
        echo '</ul>';
    }
}

printtree(parseTree($arr));
?>

Output:

• 102
  • 103
    • 216
      • 217
      • 88
  • 104

small CSS one could use :-

li 
    { 
        position: relative; 
        margin-left: -15px;
        list-style: none;
    }