未定义的变量!该怎么解决

未定义的变量!
源代码！

function OpenDB($SQL){
$link = mysql_connect($server_DB, $user_DB, $password_DB)or die("Could not connect:".mysql_error());
mysql_select_db($database_DB, $link);
$result = mysql_query($SQL);
return $result;
}

OpenDB("select * from config WHERE ID = 1");
$row = mysql_fetch_array($result);
echo $row["className"];

错误提示！
Notice: Undefined variable: result in E:\wwwroot\include\config.int.php on line 36
Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in E:\wwwroot\include\config.int.php on line 36

[解决办法]
$result=OpenDB("select * from config WHERE ID = 1");
$row = mysql_fetch_array($result);