PHP实例教程：网站在线人数的程序代码，后台有MYSQL数据库支持。可以直接统计出网站当前的在线人数。

首先是创建MYSQL数据库表。

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

可以使用的SQL语句。

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)
);

下面我们开始使用PHP脚本，首先定义MYSQL的信息。

server = "localhost"; //你的服务器
db_user = "root"; //你的mysql的用户名
db_pass = "password"; //你的mysql的密码
database = "users"; //表的名字

设置统计的时间(多少秒内在线人数)

timeoutseconds = 300;

取当前时间。

timestamp = time();

上面的完整代码：

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;
?>

连接mysql

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

也允许使用变量形式。

mysql_connect(server, db_user, db_pass);

如果mysql数据库没有密码的话可以使用下面代码连接（当然建议大家一定要设置好自己的密码，这样起码黑客得要解密啊）

mysql_connect(server, db_user);

查询数据库的代码：

mysql_db_query('database', 'query');

我们只要有访客就要增加一条记录。

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

然后我们给出如果用户用错误信息的处理方式。

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

然后我们得实现当超过我们设置的时间我们就要删除该用户记录。

delete = mysql_db_query(database, "DELETE FROM useronline WHERE timestamp

同样给出删除记录出错的处理。

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

下面我们显示数据库中有多少个不同的IP

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

我们使用

mysql_num_rows(query);

来统计用户，代码如下。

user = mysql_num_rows(result);

最后我们要关闭数据库。

mysql_close();

显示在线的人数。

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

最终把上面代码写成一个PHP文件如下。

//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 timestampif(!(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");
}
?>