create table users
(
id bigint primary key,
name varchar not null
);
insert into users
values (1, 'john'),
(2, 'Liza'),
(7, 'Odin'),
(11, 'donatello'),
(17, 'spider-man'),
(19, 'Elen'),
(20, 'Liza');
create table orders
(
id bigint primary key,
user_id bigint not null,
product varchar not null,
constraint fk_orders_user_id foreign key (user_id) references users (id)
);
insert into orders
values (101, 17, 'pizza'),
(107, 2, 'toothpaste'),
(108, 19, 'candies'),
(109, 20, 'pizza'),
(200, 17, 'shampoo'),
(205, 2, 'pizza'),
(210, 19, 'toothpaste'),
(220, 19, 'pizza'),
(221, 11, 'shampoo'),
(222, 19, 'pizza');
SELECT u.id, u.name FROM (SELECT DISTINCT user_id FROM orders) o
LEFT JOIN users u ON u.id = o.user_id
ORDER BY LOWER(u.name) ASC, u.id ASC;
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