Recursive tree traversal with mysql through PHP

Question

I am creating a questionnaire for a client that requires the questions to be organized by 3 layers of levels. I\'ve successfully created the U.I. however I\'ve been trying f

Answer 1

it's not good to call mysql server and fetch result each time

what if you have over 100 rows? or 200+

use this to query only once:

$result = mysql_query("SELECT * FROM test");
$arrs = array();

while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
    $arrs[] = $row;
}

function build_tree($arrs, $parent_id=0, $level=0) {
    foreach ($arrs as $arr) {
        if ($arr['parent_id'] == $parent_id) {
            echo str_repeat("-", $level)." ".$arr['name']."
";
            build_tree($arrs, $arr['id'], $level+1);
        }
    }
}

build_tree($arrs);

common example for table

  id    name    parent_id