@app.route('/' , methods=['GET','POST'])
def show_main():
	db = get_db()
	authors_books = execute_db('''select book_title, author_name FROM authors_books order by book_title''', db)
	books = execute_db('''select book_title FROM books order by book_title''', db)
	authors = execute_db('''select author_name FROM authors order by author_name''', db)
	form = AddInLibForm()
	choices = []
	for author in authors:
		choices.append(str(author))	
	form.select_author.choices = choices

<form action="" method=get name="add_in_lib_form">
			{{form.hidden_tag()}}
			<dl>
				<select title="Select author:">
					{% for author in form.select_author.choices %}
						<option value={{ author }}>{{ author }}</option>
					{% endfor %}	
				</select>
				<select title="Select book:">
					{% for book in form.select_book.choices %}
						<option value={{ book }}>{{ book }}</option>
					{% endfor %}	
				</select>	
				<dd><input type=submit value=Add>
			</dl>
		</form>