Как объединить в один запрос?

SELECT поле1, поле2, поле3, users_2.title as user_2_title, users_3.title as user_3_title
FROM таблица1
left join users as users_2 on  users_2.id = таблица1.поле2
left join users as users_3 on  users_3.id = таблица1.поле2
WHERE поле4 = '10';

SELECT `login` FROM `users` WHERE `id` = `поле2`
UNION
SELECT `login` FROM `users` WHERE `id` = `поле3`;

SELECT `login` FROM `users` WHERE `id` = `поле2` OR `id` = `поле3`;