小编Rol*_*ruz的帖子

我有这个设置

attendance table:
------------------------------------------
| member_id | attendance_date | event_id |
------------------------------------------

attendance indeces
---------------------------------------------
| p1 (member_id, attendance_date, event_id) |
| p2 (attendance_date, member_id, event_id) |
| member (member_id)                        |
| total (attendance_date, event_id)         |
---------------------------------------------

members table
-------------------------------------------------
| member_id | department_id | registration_date |
-------------------------------------------------

members indeces:
-----------------------------------------------
| PK (member_id)                              |
| registration (registration_date, member_id) |
| department (department_id, member_id)       |
-----------------------------------------------

所以基本上这是一个考勤系统。我需要根据出勤表运行报告。除了我需要知道成员在给定时间内缺席的次数之外，我已经弄清楚了大部分所需的查询。我几乎知道如何查询那里的数据。但我不知道如何查询不存在的数据（缺失）。

我试过这个：

SELECT
  attendance_date,
  COUNT(DISTINCT event_id)
FROM
  attendance
WHERE
  WEEKOFYEAR(attendance_date) BETWEEN 27 AND 31 …