//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);
?>