"I allow users to add tables to the database." - I hope all your users are benevolent and trustworthy and capable. Do you worry about people dropping or truncating tables, creating incorrect new tables that break your code, or other things like that? What kind of security do you have when users can log right into your database and change the schema?
Here's a tutorial on relational database normalization. Maybe it'll help.
Just in case someone else that comes after you wants to find what this could have looked like, here's a single table that could do what you want:
create database bookfeather;
create user bookfeather identified by 'bookfeather';
grant all on bookfeather.* to 'bookfeather'@'%';
use bookfeather;
create table if not exists book
(
id int not null auto_increment,
title varchar(255) not null default '',
upvotes integer not null default 0,
downvotes integer not null default 0,
primary key(id),
unique(title)
);
You'd vote a title up or down with an UPDATE:
update book set upvotes = upvotes + 1 where id = ?
Adding a new book is as easy as adding another row:
insert into book(title) values('grails in action')
I'd strongly urge that you reconsider.