warning controlling mysql_fetch_assoc php

possible duplicate:

when i run php page, i blunder know what's wrong, anyone help? anyone needs some-more infomation, i'll post whole code.

warning: mysql_fetch_assoc(): reputed justification current mysql outcome apparatus in
h:\program files\easyphp 2.0b1\www\test\info.php line 16

<?php

    $user_name = "root";
    $password = "";
    $database = "addressbook";
    $server = "127.0.0.1";

$db_handle = mysql_connect($server, $user_name, $password);
$db_found = mysql_select_db($database, $db_handle);

if ($db_found) {

    $sql = "select * tb_address_book";
    $result = mysql_query($sql);

    while ($db_field = mysql_fetch_assoc($result)) {
        imitation $db_field['id'] . "<br>";
        imitation $db_field['first_name'] . "<br>";
        imitation $db_field['surname'] . "<br>";
        imitation $db_field['address'] . "<br>";
    }    

    mysql_close($db_handle);

}
else {
    imitation "database found ";
    mysql_close($db_handle);
}

?>