common.php

<?php
include('database.php');
    if( !isset( $_SESSION ) )
    session_start();
    $errormsgs = array();
    function execute($query,$array)
    {
        $conn = connect();
        $result = $conn->prepare($query);
        $result->execute($array);

        return $result;
    }

    function searchAll($firstName,$lastName)
    {
        $query = 'SELECT movies.name AS title, movies.year
            FROM actors INNER JOIN roles
            ON actors.id = roles.actor_id
            JOIN movies
            ON roles.movie_id = movies.id
            WHERE  actors.first_name = ?
            AND actors.last_name = ?
            ORDER BY movies.year DESC';
        return execute($query,array($firstName,$lastName));
    }

    function searchKevin($firstName,$lastName)
    {
        $query = 'SELECT  movies.name AS title, movies.year
             FROM movies
            WHERE movies.id
            IN
            (SELECT actor.movie_id FROM
            (SELECT roles.movie_id FROM roles
            INNER JOIN actors On roles.actor_id = actors.id
            WHERE actors.first_name = ?
            AND actors.last_name = ?
            ) actor INNER JOIN
            (SELECT roles.movie_id FROM roles
            INNER JOIN actors ON roles.actor_id = actors.id
            WHERE actors.first_name = "Kevin"
            AND actors.last_name = "Bacon"
            ) kevin
            ON actor.movie_id = kevin.movie_id )';
        return execute($query,array($firstName,$lastName));
    }

    function validate($firstName,$lastName)
    {
        return(validateFirstName($firstName)&&validateLastName($lastName));
    }

    function validateFirstName($name)
    {   if($name==null)
        {
            $_SESSION['empty_first_name'] = "Please enter actor's first name!";
            return false;
        }
        if (!preg_match("/^[a-zA-Z]*$/",$name))
        {
            $_SESSION['name'] = "Invalid first name!";
            return false;
        }else return true;
    }

    function validateLastName($lastName)
    {   if($lastName == null)
        {
            $_SESSION['empty_last_name'] = "Please enter actor's last name!";
            return false;
        }
        if (!preg_match("/^[a-zA-Z]*$/",$name))
        {
            $_SESSION['name'] = "Invalid first name!";
            return false;
        }else return true;
    }