Задание на Select

CREATE TABLE author (
 author_id SERIAL PRIMARY KEY,
 author_name TEXT NOT NULL
);
 
CREATE TABLE reader (
 reader_id SERIAL PRIMARY KEY,
 reader_name TEXT NOT NULL,
);
 
CREATE TABLE topic (
topic_id SERIAL PRIMARY KEY,
topic_name TEXT NOT NULL,
topic_desc TEXT,
added TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(),
author_id INT NOT NULL REFERENCES author (author_id)
);
 
CREATE TABLE message (
 message_id SERIAL PRIMARY KEY,
 topic_id INT NOT NULL REFERENCES topic (topic_id),
 author_id INT NOT NULL REFERENCES author (author_id),
 added TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(),
 rating INT NOT NULL DEFAULT 0,
 message TEXT NOT NULL,
 message_is_deleted BOOLEAN DEFAULT FALSE
);
 
CREATE TYPE log_acton_type AS ENUM ('readed', 'edited', 'deleted');
 
CREATE TABLE message_log (
 message_log_id SERIAL PRIMARY KEY,
 message_id INT NOT NULL REFERENCES message (message_id),
 author_id INT REFERENCES author (author_id),
 reader_id INT REFERENCES reader (reader_id),
 message_log_action_type log_acton_type NOT NULL,
 message_log_added TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now()
);