網站在線人數的程序代碼，后臺有MYSQL數據庫支持。可以直接統計出網站當前的在線人數。

首先是創建MYSQL數據庫表。

CREATE TABLE tablename (
field type(max_length) DEFAULT 'default_value' (NOT) NULL
}

可以使用的SQL語句。

CREATE TABLE useronline (
timestamp int(15) DEFAULT '0' NOT NULL,
ip varchar(40) NOT NULL,
file varchar(100) NOT NULL,
PRIMARY KEY (timestamp),
KEY ip (ip),
KEY file (file)
);

下面我們開始使用PHP腳本，首先定義MYSQL的信息。

server = "localhost"; //你的服務器
db_user = "root"; //你的mysql的用戶名
db_pass = "password"; //你的mysql的密碼
database = "users"; //表的名字

設置統計的時間(多少秒內在線人數)

timeoutseconds = 300;

取當前時間。

timestamp = time();

上面的完整代碼：

<?php
server = "localhost"; //your server
db_user = "root"; //your mysql database username
db_pass = "password"; //your mysql database password if any
database = "users"; //the db name
timeoutseconds = 300;//timeoutseconds limit
//get the current time
timestamp = time();
//calculate the lowest timestamp allowed
timeout = timestamp-timeoutseconds;
?>

連接mysql

mysql_connect('localhost', 'username', 'password');

也允許使用變量形式。

mysql_connect(server, db_user, db_pass);

如果mysql數據庫沒有密碼的話可以使用下面代碼連接（當然建議大家一定要設置好自己的密碼，這樣起碼黑客得要解密啊）

mysql_connect(server, db_user);

查詢數據庫的代碼：

mysql_db_query('database', 'query');

我們只要有訪客就要增加一條記錄。

insert = mysql_db_query(database, "INSERT INTO useronline VALUES
('timestamp','"._SERVER['REMOTE_ADDR']."','"._SERVER['PHP_SELF']."')");

然后我們給出如果用戶用錯誤信息的處理方式。

if(!(insert)) {
print "Useronline Insert Failed > ";
}

然后我們得實現當超過我們設置的時間我們就要刪除該用戶記錄。

delete = mysql_db_query(database, "DELETE FROM useronline WHERE timestamp<timeout");

同樣給出刪除記錄出錯的處理。

if(!(delete)) {
print "Useronline Delete Failed > ";
}

下面我們顯示數據庫中有多少個不同的IP

result = mysql_db_query(database, "SELECT DISTINCT ip FROM useronline WHERE file='"._SERVER['PHP_SELF']."' ");

我們使用

mysql_num_rows(query);

來統計用戶，代碼如下。

user = mysql_num_rows(result);

最后我們要關閉數據庫。

mysql_close();

顯示在線的人數。

if(user == 1) {
print("1 user online/n");
} else {
print("user users online/n");
}

最終把上面代碼寫成一個PHP文件如下。

<?php
//Put your basic server info here
server = "localhost"; //normally localhost
db_user = "root"; //your MySQL database username
db_pass = "password"; //your MySQL database password
database = "users";
timeoutseconds = 300; //it will delete all people which haven't refreshed(so probbably are
// offline or inactive) in timieoutseconds time (so it actually checks the people that are active in the last
// timeoutseconds seconds)
//this is where PHP gets the time
timestamp = time();
//counts the timeout, all people which have been seen last online in earlier than this timestamp, will get removed
timeout = timestamp-timeoutseconds;
//connect to database
mysql_connect(server, db_user);
//add the timestamp from the user to the online list
insert = mysql_db_query(database, "INSERT INTO useronline VALUES
('timestamp','"._SERVER['REMOTE_ADDR']."','"._SERVER['PHP_SELF']."')");
if(!(insert)) {
print "Useronline Insert Failed > ";
}
//delete the peoples which haven't been online/active in the last timeoutseconds seconds.
delete = mysql_db_query(database, "DELETE FROM useronline WHERE timestamp<timeout");
if(!(delete)) {
print "Useronline Delete Failed > ";
}
//select the amount of people online, all uniques, which are online on THIS page
result = mysql_db_query(database, "SELECT DISTINCT ip FROM useronline WHERE file='"._SERVER['PHP_SELF']."' ");
if(!(result)) {
print "Useronline Select Error > ";
}
//Count the number of rows = the number of people online
user = mysql_num_rows(result);
//spit out the results
mysql_close();
if(user == 1) {
print("1 user online/n");
} else {
print("user users online/n");
}
?>