YA: Simple Login Processing 20130513042043AAQO7yN

<?php
// In response to http://answers.yahoo.com/question/index?qid=20130513042043AAQO7yN


// Variables
$html_header;
$message;
$user = (isset( $_POST['user'] ))? trim( $_POST['user'] ) : '';
$pass = (isset( $_POST['password'] ))? trim( $_POST['password'] ) : '';


// Check First For POST, no need to use a connection before needed.

if( strlen($user) > 0 && strlen($pass) > 0){
    // Database Connection ( You should be at least be using MySQLi )
    $conn = mysql_connect( 'localhost', 'username', 'passowrd' );
    if( !$conn ){ // Check For Connection
        if( !mysql_select_db( 'twa051', $conn ) ){
            $message = 'Cannot Select MySQL Database.<br /> Reason: ' . mysql_error($conn);
        }
    }else{
        $message = 'Cannot Connect To MySQL.<br /> Reason: ' . mysql_error($conn);
    }

    // If there's no message, then there's no problems
    if( is_null($message) ){
        // MySQL injection protection (look into PDO)
        $user = mysql_real_escape_string( $user );
        $pass = mysql_real_escape_string( $pass );

        // I'm using 'id' but substitute for whatevery key column you're using
        $query = "SELECT id FROM school_info WHERE username='{$user}' AND password='{$pass}' LIMIT 1";

        $results = mysql_query( $query );

        if( !$results ){
            $message = 'Malformed Query Statement, Or , Internal Error.<b' . 'r />' . mysql_error( $conn );
        }else if( mysql_num_rows( $results ) === 1){ // If it returns a row, then the username and password match.
            $html_header = '<meta http-equiv="refresh" content="0;URL=home.php">';
            header('Location: home.php');
        }else{
            $message = 'Incorrect Username/Password combo.';
        }
    }
}else if( $_SERVER[ 'REQUEST_METHOD' ] === 'POST'){
    $message = 'Please Enter Both Username and Password.';
}else{
    $message = 'Please Enter Username and Password.';
}
?><!DOCTYPE html>
<html>
    <head>
        <title> Form </title>
        <link rel="Stylesheet" type="text/css" href="form.css" />
        <?php if( !is_null($html_header) ){ echo $html_header;} ?>
    </head>
    <body>
        <p>
            <a href="home2.html" >Back to homepage </a>
        </p>
        <img src="logo.png" width="150" height="80" alt="Logo" />
        <br />
        <br />
        <br />
        <br />
        <p>
            <?php echo $message; ?>
        </p>
        <p style="border: 1px solid #333;">
            <form method="post" action="login.php">
                <label>
                    Username:
                </label>
                <input type="text" name="user" />
                <br />
                <label>
                    Password:
                </label>
                <input type="password" name="password"/>
                <br />
                <input type="submit" value="Login" />
                <input type="reset" value="Reset" />
            </form>
        </p>
    </body>
</html>