CREATE TABLE users (
id SERIAL NOT NULL PRIMARY KEY
);
CREATE TABLE comments (
id SERIAL NOT NULL PRIMARY KEY,
user_id INT NOT NULL,
created_at TIMESTAMP NOT NULL DEFAULT NOW(),
CONSTRAINT fk_users_comment FOREIGN KEY (user_id) REFERENCES users (id)
ON UPDATE CASCADE
ON DELETE CASCADE
)
SELECT u.id
FROM comments c
LEFT JOIN users AS u ON u.id = c.user_id
WHERE c.created_at > to_timestamp('01.01.2019', 'DD.MM.YYYY')
AND c.created_at < to_timestamp('01.02.2019', 'DD.MM.YYYY')
GROUP BY u.id
Простой
Средний
Простой
Простой
