Answer 1

Answer 2

Answer 3

对于SQL Server 2008及更高版本，我想使用通用表表达式向查询中添加聚合列：

WITH AttendanceTimes (course_id, maxTime)
AS 
(
    SELECT
        course_id,
        MAX(attendance_time)
    FROM attendance
    GROUP BY course_id
)

SELECT
    a.course_id,
    t.maxTime,
    a.id
FROM attendance a
INNER JOIN AttendanceTimes t
ON a.course_id = t.course_id