_php skills of online people function library implemented by PHP

Increase user
function AddUser ($username) {
Global $db;
$Ip =getenv (' remote_addr ');
$Ip 1 = getenv (' http_x_forwarded_for ');
if ($Ip 1!= "") && ($Ip 1!= "Unknown")) $Ip = $Ip 1;
$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 Online user list
function Updatemember () {
Global $db;
$SQL = "Delete from Class_online where Unix_timestamp ()-unix_timestamp (lasttime) >180"; 3 minutes inactive Then exit
Echo $SQL;
mysql_query ($SQL, $db);
}
Update online status
function Updateonline ($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, $db);
}
Delete User
function Outoneuser ($user) {
Global $db;
$SQL = "Delete from class_online where user= ' $user '";
mysql_query ($SQL, $db);
return true;
}
Check whether online
function CheckUser ($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;
}
Take 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;
}
Online People function library ***************end