Question

This is my database project.

table user_

select id, name from user_;

 id |   name
----+----------
  1 | bartek
  2 | bartek_m
  3 | bartek_k
  4 | bartek_b

table order_

select id, employee_id, user_id from order_;

 id | employee_id | user_id
----+-------------+---------
  1 |           3 |       1
  2 |           4 |       1
  3 |           4 |       1
  4 |           4 |       1
  5 |           3 |       1

Every user has a role(I don’t add table role_ here but it exist).
ID of every user with role employee can be assigned to order_.employee_id
I need obtain user with minimum number of orders

select a.id, min(a.count) from (
    select u.id, count(u.id) from user_ u, order_ o
    where u.id = o.employee_id
    group by u.id
) as a group by a.id, a.count

 id | min
----+-----
  4 |   3
  3 |   2

I think that my query is wrong. Could anyone change query to return
only ID this user which have minimum number of orders?

Answer 1

Like

SELECT u.id, count(*)
FROM user_ AS u JOIN order_ AS o ON (u.id=o.employee_id)
GROUP BY u.id
ORDER BY 2 LIMIT 1

(if I read you right)?