Design an Online Chat Room with PHP and MySQL

Step 1: Design Database Table. Create table "chat" in MySQL database to store basic chat information: chtime (chat time), nick (user nickname) and words (chat message, less than 150 characters)

mysql> CREATE TABLE chat

-> chtime DATATIME,

-> nick CHAR (10) NOT NULL,

-> words CHAR (150);

Step 2: Design Structure. This simple online chat room includes the following four sections: user login, message display, message input and a main frame integrating the display and input sections. Thus, it needs the following four files to work: login.php, main.php, display.php and speak.php.

Step 3: Write the code

1. login.php (just a HTML form)

Please input your nickname and enter

2. main.php

setcookie("nick",$nick) //use cookie to store user nickname

?>

3. display.php

This file is used to get message records from database and display the results. To keep the size of database, old messages are deleted and only the newest 15 messages are displayed.

//connect to mysql server, server name: main, database username: root

$link_ID=mysql_connect("main","root");

mysql_select_db("abc"); //abc is the database name

$str="select * from chat ORDER BY chtime;" ;

$result=mysql_query($str, $link_ID);

$rows=mysql_num_rows($result);

//get the latest 15 messages

@mysql_data_seek($resut,$rows-15);

//if the number of messages<15, get all of the messages

if ($rows<15) $l=$rows; else $l=15; for ($i=1;$i<=$l; $i++) {

list($chtime, $nick, $words)=mysql_fetch_row($result);

echo $chtime; echo " "; echo $nick; echo":" ; echo $words; echo "

";

} //delete the old messages(only keep the newest 20 only)

@mysql_data_seek($result,$rows-20);

list($limtime)=mysql_fetch_row($result);

$str="DELETE FROM chat WHERE chtime<'$limtime' ;" ;

$result=mysql_query($str,$link_ID);

mysql_close($link_ID);

?>

4. speak.php

If ($words)

{ $link_ID=mysql_connect("main","root");

mysql_select_db("abc"); // abc is the database name

$time=date(y).date(m).date(d).date(h).date(i).(date(s); //get current time

$str="INSERT INTO chat(chtime,nick,words) values ('$time','$nick','$words');" ;

mysql_query($str,$link_ID); //save message record into database

mysql_close($link_ID); )

?>

//the following is the message input form

Now, you have finished the design and coding of a simple online chat system. Put all the files into your website root and see how it works, :)