在MySQL中连接表和聚合数据？

Question

我有2张桌子。 会员及其项目。 我需要提取所有用户，他们的项目数量，按项目数量排序。

表： users ：

id | username | email | password | reg_date

表： projects ：

id | title    | descr | autor

对于加入：

projects.autor = users.id

Answer 1

SELECT
  users.id,
  users.username,
  COUNT(projects.id) AS `num_projects`
FROM
  users
LEFT OUTER JOIN
  projects
ON
  projects.autor = users.id
GROUP BY
  users.id
ORDER BY
  num_projects DESC

Answer 2

SELECT u.id AS id, u.username AS username, u.email AS email, u.password AS password, u.reg_date AS reg_date, COUNT(p.id) AS projects_count 
FROM users u
LEFT OUTER JOIN projects p ON p.autor = u.id
GROUP BY u.id 
ORDER BY projects_count DESC