Untitled

<?php
	require("dekey.php");
?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
<title>Student Data</title>
</head>

<body>
Select a major:<br/>
<form name="form" method="post" action="<?php echo $_SERVER['PHP_SELF']?>">

	<select name="major">
		  <option value="">-</option>
          <option value="CIS">CIS</option>
          <option value="ISI">ISI</option>
     </select>
     <br /><br />
     <input type="submit" name="Submit" value="Submit">
</form>

<?php
if(isset($_POST['Submit'])){
    main();
}

function main(){
    $link = connectDB();

    $major=trim($_POST['major']);
    if(verify($major)){
        $prepared = queryData($link, $major);
        showData($prepared);
    }else{
        echo "<p>Please select a major</p>";
    }
    mysqli_close($link);
}

function connectDB(){
    dekey_main();

    $host = trim ($GLOBALS['host']);
    $username = trim ($GLOBALS['username']);
    $password = trim ($GLOBALS['password']);
    $db = trim ($GLOBALS['db_name']);

    $myDB = mysqli_connect($host, $username, $password, $db);

    if(mysqli_connect_error()){
        echo "connection error";
        exit;
    }
    return $myDB;
}


function verify($major){
        $isValid = false;
        $major=mb_convert_encoding($major);
        $regEx ="^[a-zA-Z]{3,7}$";
        if(size(preg_match($regEx, $major)) > 1){
            $isValid=true;
        }
        return $isValid;
    }


function  queryData($link, $major){
    $major=trim($major);

    if($major=="CIS" || $major=="ISI"){
        $studentQuery="SELECT lastname, firstname, major FROM Students";
        $prepared=mysqli_prepare($link, $studentQuery);
        mysqli_stmt_bind_param($prepared, "s");
        $result=mysqli_stmt_execute($prepared);
        if($result){
            return $prepared;
        }
    }
    return null;
}


function showData($prepared){
    if(!is_null($prepared)){
        echo "<table border='0'>";
        echo "<tr>";
        echo "<td> Last Name</td>";
        echo "<td> First Name</td>";
        echo "<td> Major</td>";
        echo "</tr>";
        mysqli_stmt_bind_result ($prepared, $lastName, $firstName, $major);

        while (mysqli_stmt_fetch($prepared)) {
            echo "<tr>";
            echo "<td>$lastName</td>";
            echo "<td>$firstName</td>";
            echo "<td>$major</td>";
            echo "</tr>";
        }
        echo "</table>";
        }else{
            mysqli_stmt_error($prepared);
        }
    }
?>

</body>
</html>