Sistema de preguntas y respuestas

qax.sql

create table users(
id int not null primary key,
name varchar(50) not null,
lastname varchar(50) not null,
username varchar(50),
email varchar(255) not null,
password varchar(60) not null,
image varchar(255) not null,
is_active boolean not null,
is_admin boolean not null,
created_at timestamp not null
);

create table category(
id int not null primary key,
name varchar(50)
);

create table question(
id int not null primary key,
title varchar(255),
description text,
tags varchar(255),
user_id int not null,
category_id int,
is_solved boolean not null,
created_at timestamp not null,
foreign key (user_id) references users(id),
foreign key (category_id) references category(id)
);

create table answer(
id int not null primary key,
description text,
user_id int not null,
question_id int,
is_correct boolean not null,
created_at timestamp not null,
foreign key (user_id) references users(id),
foreign key (question_id) references question(id)
);

create table vote(
id int not null primary key,
kind_id int, /** 1.- question, 2.- answer **/
ref_id int,
val int not null,
created_at timestamp not null,
user_id int not null,
foreign key (user_id) references users(id)
);