Online staff function library implemented by php

I used to find... online staff Library // add users
Function AddUser ($ username ){
Global $ db;
$ Ip = getenv ('remote _ ADDR ');
$ Ip1 = getenv ('http _ X_FORWARDED_FOR ');
If ($ Ip1! = "") & ($ Ip1! = "Unknown") $ Ip = $ Ip1;
$ Current_time = date ("Y-m-d H: I: s ");
$ SQL = "select user from class_online where user = '$ username '";
$ Res = mysql_query ($ SQL, $ db );
$ Row = @ mysql_num_rows ($ res );
If ($ row = 0 ){
$ SQL = "insert into class_online (user, ip, lasttime) values ('$ username',' $ IP', '$ current_time ')";
Mysql_query ($ SQL, $ db );
}
}
// Update the online user name list
Function UpdateMember (){
Global $ db;
$ SQL = "delete from class_online where UNIX_TIMESTAMP ()-UNIX_TIMESTAMP (lasttime)> 180"; // exit if you are not active for 3 minutes
// Echo $ SQL;
Mysql_query ($ SQL, $ db );
}
// Update the online status
Function UpdateOnline ($ username ){
Global $ db;
$ Current_time = date ("Y-m-d H: I: s ");;
$ SQL = "update class_online set lasttime = '$ current_time' where user = '$ username '";
$ Res = mysql_query ($ SQL, $ db );
}
// Delete a user
Function OutOneUser ($ user ){
Global $ db;
$ SQL = "delete from class_online where user = '$ user '";
Mysql_query ($ SQL, $ db );
Return true;
}
// Check whether it is online
Function CheckUser ($ user ){
Global $ db;
$ SQL = "select user from class_online where user = '$ user '";
$ Res = mysql_query ($ SQL, $ db );
$ Row = mysql_num_rows ($ res );
If ($ row> 0) return true;
Else return false;
}
// Obtain the online list
Function ReadOnlineName (){
Global $ db;
$ SQL = "select * from class_online ";
$ Res = mysql_query ($ SQL, $ db );
While ($ row = mysql_fetch_array ($ res )){
$ Result [] = $ row [user];
}
Return $ result;
}
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