U138

CREATE TABLE products
(id integer);

INSERT INTO products
VALUES (1),
       (2),
       (3);

CREATE TABLE sellers
(email varchar);

INSERT INTO sellers
VALUES ('email1@gmail.com'),
       ('email2@gmail.com'),
       ('email3@gmail.com');

CREATE TABLE sales
(id serial, kedy timestamp, price numeric, product_id integer, seller_id varchar);

INSERT INTO sales (kedy, price, product_id, seller_id)
SELECT
TIMESTAMP '2011-11-11' + floor((random() * 365)) * INTERVAL '1 day',
floor(random() * 50 + 5)::numeric AS price,
products.id AS product_id,
sellers.email AS seller_id
FROM products, sellers
WHERE random() > 0.5;