login.php

session_start(); // Starting Session
$error=''; // Variable To Store Error Message
if (isset($_POST['submit'])) {
if (empty($_POST['username']) || empty($_POST['password'])) {
$error = "Username or Password is invalid";
}
else
{
// Define $username and $password
$username=$_POST['username'];
$password=$_POST['password'];
$errors = array();

	if ((strlen($username) == 0) || (strlen($password) == 0)){
		array_push($errors, "You must enter a valid username and Password");
	}
// Establishing Connection with Server by passing server_name, user_id and password as a parameter
		$query = "SELECT COUNT(*) AS NUMBER_OF_ROWS FROM ( SELECT * FROM users WHERE Username  = '$username' AND Password = '$password' )";
		//$query ="SELECT * FROM users WHERE Username  = '$username' AND Password = '$password'";
...//connection stuff



// SQL query to fetch information of registerd users and finds user match.
$stmt = oci_parse($connect, $query);
if(!$stmt) {
		echo "An error occurred in parsing the sql string.\n";
		exit;
		}
oci_define_by_name($stmt, 'NUMBER_OF_ROWS', $rows);
oci_execute($stmt);
oci_fetch($stmt);

if ($rows == 1) {
	$error = "You have successfully logged in";
	$query ="SELECT ROW FROM users WHERE Username  = '$username' AND Password = '$password'";
	$stmt = oci_parse($connect, $query);
	oci_execute($stmt);
	$_SESSION['login_user']=$username; // Initializing Session
header("location: myaccount.php"); // Redirecting To Other Page
} else {
$error = "Username or Password is invalid" . $row;
}
 // Closing Connection
}
}

end login.php

signin.php

include('login.php'); // Includes Login Script

if(isset($_SESSION['login_user'])){
header("location: myaccount.php");
}

...

<p class="details">
             Login or create and Account
			 <?php echo $error; ?>
            </p>

              	<div class="contact_form">
                <div class="form_subtitle">login into your account</div>
                 <form name="Login" method="POST">
                    <div class="form_row">
                    <label class="contact"><strong>Username:</strong></label>
                    <input id="name" name="username" placeholder="username" type="text">
                    </div>


                    <div class="form_row">
                    <label class="contact"><strong>Password:</strong></label>
                    <input id="password" name="password" placeholder="**********" type="password">
                    </div>

                    <!--<div class="form_row">
                        <div class="terms">
                        <input type="checkbox" name="terms" />
                        Remember me
                        </div>
                    </div> -->


                    <div class="form_row">
                    <input name="submit" type="submit" class="Login" value="login" />
                    </div>

                  </form>