执行php脚本出错

[Snymph]

Warning: mysql_db_query(): supplied argument is not a valid MySQL-Link resource in /usr/local/apache/htdocs/msg.php on line 23

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /usr/local/apache/htdocs/msg.php on line 24


源代码是这样的：
function assign_id()
{
$query="select max(msgid) from msg";
$result=mysql_db_query("topic",$query,$link);
$a=mysql_fetch_array($result);//line 23
$this->msgid=$a[0]+1;//line 24
}

[Snymph]

哦，对，是在外边声明的
呵呵！

[hodat]

function assign_id()
{
$query="select max(msgid) from msg";
$result=mysql_db_query("topic",$query,$link);
$a=mysql_fetch_array($result);//line 23
$this->msgid=$a[0]+1;//line 24
}

$link是个外步变量吧~~

要加

global $link哦~~