可以实现在线人数统计，日访问量统计，月访问量统计。。。。。

<?
$sql = "CREATE TABLE guestinfo(id integer DEFAULT '0' NOT NULL       AUTO_INCREMENT,
                       ipaddress varchar(20),
                       host      varchar(20),
                       cometime    datetime,
                       refreshtime datetime,
                       leavetime  datetime,
                       PRIMARY KEY(id),
                       UNIQUE id(id),
                       index guestinfo(id)
                       )";
   mysql_query($sql, $connect);
?

<?
    $duration = 300;
    $sql = "select * from guestinfo where  (leavetime is null or leavetime='') and ( UNIX_TIMESTAMP(NOW())-UNIX_TIMESTAMP(refreshtime))$duration";
    $result=@mysql_query($sql);
    while($row=@mysql_fetch_array($result))
    {
        $id = $row['id'];
        $sql = "update guestinfo set leavetime=now() where id='$id'";
        mysql_query($sql);

    }
    $sql = "select * from guestinfo where ipaddress='$REMOTE_ADDR' and (leavetime is null or leavetime='')";
    $result = @mysql_query($sql);
    if($row=@mysql_fetch_array($result))
    {
       $id = $row['id'];
       $sql="update guestinfo set refreshtime=now() where id='$id'";
       mysql_query($sql);
    }
    else
    {
       $sql = "insert into guestinfo(ipaddress,host,cometime,refreshtime)
          values('$REMOTE_ADDR','$REMOTE_HOST',now(),now())";
       mysql_query($sql);
    }
    $date= mktime(0,0,0,date("m"),date("d"),date("Y"));
    $sql = "select count(*) from guestinfo where  UNIX_TIMESTAMP(refreshtime) $date";
    $result = mysql_query($sql);
    if($result)
    {
        $row = mysql_fetch_array($result);
        $todayaccess = $row["count(*)"];
    }
    else $todayaccess = 0;