How can I get mysql table definitions in my php script?

<?
$db_user = "user";
$db_pass = "password";
$db_database = "database";
$db_host = "localhost";

$db = mysql_connect($db_host, $db_user, $db_pass);
if (!$db) {
   die('Could not connect: ' . mysql_error());
}

mysql_select_db($db_database, $db);


$tables = mysql_query("show tables",$db);

while($table = mysql_fetch_array($tables)) {
        print "<b>Table: ".$table[0]."</b><br>n";
        $result = mysql_query("SHOW COLUMNS FROM ".$table[0],$db);
        if (mysql_num_rows($result) > 0) {
          print "<ul>";
          while ($row = mysql_fetch_assoc($result)) {
                if($row['Null'] == "YES") {
                        $null = "NULL";
                }
                else {
                        $null = "NOT NULL";
                }
          print "<b>".$row['Field']."</b> ".$row['Type']." $null ".$row['Key']." ".$row['Extra']." ".$row['Default']."<br>\n";
           }
          print "</ul>";
        }
}
mysql_close($db);
?>