Titanium - Insert Record.js

var adp = Titanium.API.Application.getDataPath();
    var dbpath = adp+"\\"+"sampledb.db"; 
    var db = Titanium.Database.openFile(dbpath);
 
    db.execute('CREATE TABLE IF NOT EXISTS users (id INTEGER PRIMARY KEY, firstname VARCHAR(50), lastname VARCHAR(50))');
 
    var firstname = $("input#firstname").val();
    var lastname = $("input#lastname").val();
 
    db.execute("INSERT INTO users (firstname, lastname) VALUES (?, ?)", firstname, lastname);
    alert("Added the User: " + firstname + " " + lastname);
    db.close();