COPY products(is_public, title, discount) TO 'D:\csv_backup\products_db.csv' DELIMITER ',' CSV HEADER;    

COPY categories(name) TO 'D:\csv_backup\categories_db.csv' DELIMITER ',' CSV HEADER;

COPY products TO 'D:\csv_backup\products_db.csv' DELIMITER ',' CSV HEADER;    

COPY categories TO 'D:\csv_backup\categories_db.csv' DELIMITER ',' CSV HEADER;

copy (select oid,relname from pg_class limit 5) to stdout;