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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：
<?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;
?>
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<$timeout");
同样给出删除记录出错的处理。
if(!($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。
<?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");
}
?>