PHP simplest log-in script

Overview

Create 3 files 1. main_login.php 2. checklogin.php 3. login_success.php Steps 1. Create table "members" in database "test". 2. Create file main_login.php. 3. Create file checklogin.php. 4. Create file login_success.php. 5. Create file logout.php Create table "members"     CREATE TABLE `members` ( `id` int(4) NOT NULL auto_increment, `username` varchar(65) NOT NULL default '', `password` varchar(65) NOT NULL default '', PRIMARY KEY (`id`) ) TYPE=MyISAM AUTO_INCREMENT=2 ; -- -- Dumping data for table `members` -- INSERT INTO `members` VALUES (1, 'chandrima', '1234'); Create file main_login.php //Code Create file checklogin.php //Code $host="localhost"; // Host name $username=""; // Mysql username $password=""; // Mysql password $db_name="test"; // Database name $tbl_name="members"; // Table name // Connect to server and select databse. mysql_connect("$host", "$username", "$password")or die("cannot connect"); mysql_select_db("$db_name")or die("cannot select DB"); // username and password sent from form  $myusername=$_POST['myusername']; $mypassword=$_POST['mypassword']; // To protect MySQL injection (more detail about MySQL injection) $myusername = stripslashes($myusername); $mypassword = stripslashes($mypassword); $myusername = mysql_real_escape_string($myusername); $mypassword = mysql_real_escape_string($mypassword); $sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'"; $result=mysql_query($sql); // Mysql_num_row is counting table row $count=mysql_num_rows($result); // If result matched $myusername and $mypassword, table row must be 1 row if($count==1){// Register $myusername, $mypassword and redirect to file "login_success.php" session_register("myusername"); session_register("mypassword");  header("location:login_success.php"); } else { echo "Wrong Username or Password"; } ?> Create file login_success.php //Code // Check if session is not registered , redirect back to main page.  // Put this code in first line of web page.  session_start(); if(!session_is_registered(myusername)){ header("location:main_login.php"); } ?> Login Successful Logout.php If you want to logout, create this file // Put this code in first line of web page.  session_start(); session_destroy(); ?> For PHP5 User - checklogin.php //Code ob_start(); $host="localhost"; // Host name $username=""; // Mysql username $password=""; // Mysql password $db_name="test"; // Database name $tbl_name="members"; // Table name // Connect to server and select databse. mysql_connect("$host", "$username", "$password")or die("cannot connect"); mysql_select_db("$db_name")or die("cannot select DB"); // Define $myusername and $mypassword  $myusername=$_POST['myusername']; $mypassword=$_POST['mypassword']; // To protect MySQL injection (more detail about MySQL injection) $myusername = stripslashes($myusername); $mypassword = stripslashes($mypassword); $myusername = mysql_real_escape_string($myusername); $mypassword = mysql_real_escape_string($mypassword); $sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'"; $result=mysql_query($sql); // Mysql_num_row is counting table row $count=mysql_num_rows($result); // If result matched $myusername and $mypassword, table row must be 1 row if($count==1){// Register $myusername, $mypassword and redirect to file "login_success.php" session_register("myusername"); session_register("mypassword");  header("location:login_success.php"); } else { echo "Wrong Username or Password"; } ob_end_flush(); ?>