How to implement online user list?

PHP code :? # Author: Marco (hkfuk) # Contact: Crazy_Marco@msn.com # $ hostlocalhost; // mysql host $ userroot; // mysql use? Why? Q $ pw; // password of mysql? $ Db; // mysql? Expected? Why? Q $ update_time30; // updated? PHP code:



#

# Author: Marco (hkfuk)

#

# Contact: Crazy_Marco@msn.com

#

$ Host = "localhost"; // mysql host

$ User = "root"; // mysql usage? Why? Q

$ Pw = ""; // password of mysql?

$ Db = ""; // mysql? Expected? Why? Q

$ Update_time = "30"; // updated? Rate --- seconds

Session_start ();

If (! $ _ SESSION ['name']) session_register ("name ");

######################################## ####

$ Con = mysql_connect ($ host, $ user, $ pw) or die ("no? Connected? Expected ?? Quot ;);

$ Now = time ();

Mysql_select_db ($ db, $ con) or die ("?? ? Expected ?? Db ");

If (! Empty ($ name) {// If yes? Okay? Logged on

$ Query = mysql_query ("select count (username) from online_list where username = '$ name'", $ con); // query? In? To the table? Useful? Taobana? Q

$ Result = mysql_result ($ query, 0); // query? ? Result

If ($ result! = 0) {// If? Okay? In? List

@ Mysql_query ("update online_list set second_time = '$ now' where username = '$ name'", $ con); // used for update? Why are there too many other users ?? R?

} Else {// If yes? Okay? Not in? List

@ Mysql_query ("insert into online_list (username, userip, online_time, second_time) values ('$ name',' $ REMOTE_ADDR ',' $ now ',' $ now ')", $ con); // add one ?? Use? Why? List

}

}



Else {// if Yes?] Yes

$ Query = mysql_query ("select count (userip) from online_list where userip = '$ REMOTE_ADDR'", $ con); // query? In? To the table? Yes? Customer ip address

$ Result = mysql_result ($ query, 0); // query? ? Result

If ($ result! = 0) {// If? Customer IP address already? In? List

@ Mysql_query ("update online_list set second_time = '$ now' where userip = '$ REMOTE_ADDR'", $ con); // update? What is the customer's last ?? R?

} Else {// If yes? Skew?] Yes? Customer IP address

@ Mysql_query ("insert into online_list (username, userip, online_time, second_time) values ('? Ker', '$ REMOTE_ADDR', '$ now', '$ now') ", $ con); // add a question ??? Customer arrival? List

}

}

$ Del_time = $ now-$ update_time;

@ Mysql_query ("delete from online_list where second_time <$ del_time", $ con );//? H except in $ update_time seconds?] Yes? Why ?? Br/>
?>