Listing tables from Mysql database doesn't work

[fert]

[code]
$tables=@mysql_list_tables($username);
$table_list="<form name=\"tables\">";
$table_num=0;

while($table_num<mysql_num_rows($tables))
{
$table_names[$table_num]=mysql_tablename($tables,$table_num);
$table_list.="<p><input type=\"button\" value=\"Select\" name=\"$table_names[$table_num]\" onClick=\"select($table_names[$table_num]);\">$table_names[$table_num]</p>";
$table_num++;
}
$table_list.="</form>";
[/code]
when i run this script i get: Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/content/z/z/i/zzieba/html/mysql/panel.php on line 42
what can i do to fix this?

[Barand]

try
[code]<?php
$sql = mysql_query("SHOW TABLES FROM $username") or die(mysql_error());

$table_list = "<form name=\"tables\">";

while (list($tname) = mysql_fetch_row($sql)) {
$table_list .= "<p><input type=\"button\" value=\"Select\" name=\"$tname]\" onClick=\"select($tname);\">$tname</p>";
}
$table_list .= "<form name=\"tables\">";
echo $table_list;
?>[/code]