register->
insert into users (name, surname, username, password, email, birthday) values ('Test', 'User', 'test_user', '123456', 'test@user.com', '01.01.1980');

login->
select u.* from users u where
( u.username = username_pattern or u.email = email_pattern ) and
(u.password = password_pattern);

topics for category ->
select t.* from topics t, topics_categories tc, categories c where
t.id = tc.topic_id and
tc.category_id = c.id;

last 10 topics ->
select * from (
    select * from topics
    order by created_at desc limit 10
) order by created_at ASC;

show topic->
select t.*, c.* form topics t, comments c where
t.id = requested_topic_id and
c.topic_id = t.id;

admin panel=> search users bt name, surname or email ->
select u.* from users u where
u.username like pattern or
u.name like pattern or
u.surname like pattern;

admin panel=> all users with the requested role ->
select u.* from users u, roles r where
r.id = requested_role_id and
u.role_id = r.id;

create topic->
insert into topics (title, content, tags, status) VALUES ('Topic One', 'Content of the first topic', 'tag1, tag2', true);

create comment->
insert into comments (content, topic_id, category_id) VALUES ('This is comment's content', 1, 1);