Example: 1


register.php

	<?php

       echo "<h1> Register</h1>";

	$submit = $_POST['submit'];


	//form data

	$fullname = strip_tags($_POST['fullname']);
	$username = strip_tags($_POST['username ']);
	$password = strip_tags($_POST['password ']);
	$repeatpassword =strip_tags($_POST['repeatpassword ']);
	$date = date("y-m-d");
	
	
	if($submit)

	{
	
	// check for existance
		
		if($fullname && $username && $password && $repeatpassword)

		{

			
			if($password == $repeatpassword)
			{
			
			
				//chech char length of username and fullname
				if(strlen($username) >25 || strlen ($fullname)>25)
				{
				echo "Length of username or fullname is too long!";
				}
				else
					if(strlen($password) >25 || strlen ($password)>6)
					{
					echo "Password must be between 6 and 25 characters";

					}
					else
					
					{
						//encrypt password
						$password = md5($password);
						$repeatpassword = md5($repeatpassword);
						
						//connect Database
						
						$connect = mysql_connect ("localhost","root","");
						mysql_select_db("phplogin");
						$queryreg = mysql_query("
								
						INSERT INTO user VALUES ('','$name','$username','$password','$data')
							
						");

						die("You have been registerd! <a href = 'index.php'>Return to login page</a> ";
						


					}

			

			}
			else
			
			echo "Your passwords do not match!";
			


		}

		else
		
		echo "Please fill in <b>all</b> fields!";
	
	

	}

	?>

	<html>
	<p>

	<form action='register.php' method='POST'>
	
		<table>
			<tr>
			<td>Your full name : </td>
			
			<td><input type='text' name='fullname' value='<?php echo $fullname;  ?> '></td>
			</tr>
			
			<tr>
			<td>Choose a username :  </td>
			
			<td><input type='text' name='username' value='<?php echo $username;  ?> '></td>
			</tr>

			<tr>
			<td>Choose a password :  </td>
			
			<td><input type='password' name='password'></td>
			</tr>

			<tr>
			<td>Repeat your password :  </td>
			
			<td><input type='password' name='repeatpassword'></td>
			</tr>
			<p>
			<input type='submit' name='submit' value='Register'>
			
			
		</table>
		
			
	</form>
	
	
	</html>


	
	

Example: 2


Login.php


	<?php

	session_start();

	$username = $_POST['username'];
	$password = $_POST['password'];

	if($username && $password)
	{

	$connect = mysql_connect("localhost","root","admin") or die("Couldn't connect!");
	mysql_select_db("phplogin") or die("Couldn't find db");

	$query= mysql_query("SELECT * From users WHERE username='$username'");
	$numrows = mysql_num_rows($query);

	if ($numrows!=0)
	{
	//code to login
	 while ($row = mysql_fetch_assoc($query))
	 	{
			$dbusername = $row['username'];
			$dbpassword = $row['password'];
		}
		if($username==$dbusername&&$password==$dbpassword)
		{
			echo "You're in!";
		}
		else
		 echo "Incorrect password!";
		
	}
	else
	die("That user does't exist!");

	
	}
	else
   	die("Please enter  username and Password!");

	?>






Example 3


Login.php


	<?php

	session_start();

	$username = $_POST['username'];
	$password = $_POST['password'];

	if($username && $password)
	{

	$connect = mysql_connect("localhost","root","admin") or die("Couldn't connect!");
	mysql_select_db("phplogin") or die("Couldn't find db");

	$query= mysql_query("SELECT * From users WHERE username='$username'");
	$numrows = mysql_num_rows($query);

	if ($numrows!=0)
	{
	//code to login
	 while ($row = mysql_fetch_assoc($query))
	 	{
			$dbusername = $row['username'];
			$dbpassword = $row['password'];
		}
		if($username==$dbusername && md5($password)==$dbpassword)
		{
			echo "You're in!";
		}
		else
		 echo "Incorrect password!";
		
	}
	else
	die("That user does't exist!");

	
	}
	else
   	die("Please enter  username and Password!");

	?>





Example 4


Refer the Database(MYSQL) - in this tutorial they are  Modifying  somthing in the DB








