test_db.sql

CREATE TABLE users (
  id        SERIAL PRIMARY KEY,
  name      VARCHAR(200) NOT NULL
);

insert into users (name) values ('bob'), ('tom'), ('jane'), ('mary');

CREATE TABLE sales (
  id        SERIAL PRIMARY KEY,
  user_id   int references users(id),
  value     bigint,
  sold_on   timestamptz
);

insert into sales 
  (user_id, value, sold_on) 
values 
  (1, 200, '2020-06-22 19:10:25-07'), 
  (2, 300, '2020-06-18 19:10:25-07'), 
  (3, 340, '2020-06-12 14:10:25-07'), 
  (3, 450, '2020-06-21 9:10:25-07'), 
  (4, 250, '2020-06-20 19:10:25-07');