sql - 将子选择值与主选择中的值进行比较

Question

在 MS Access 中，我有一个查询，我想使用外部查询中的列作为内部查询中的条件：

SELECT P.FirstName, P.LastName, Count(A.attendance_date) AS CountOfattendance_date,
       First(A.attendance_date) AS FirstOfattendance_date,
       (SELECT COUNT (*) 
          FROM(SELECT DISTINCT attendance_date 
                FROM tblEventAttendance AS B 
                WHERE B.event_id=8 
                  AND B.attendance_date >= FirstOfattendance_date)
       ) AS total
FROM tblPeople AS P INNER JOIN tblEventAttendance AS A ON P.ID = A.people_id
WHERE A.event_id=8
GROUP BY P.FirstName, P.LastName
;

关键点是FirstOfattendance_date- 我希望子选择中的比较深入使用主选择的每次迭代中的值。显然这不起作用，它会询问我FirstOfattendance_date何时尝试运行它的值。

我想在不诉诸VB代码的情况下做到这一点......有什么想法吗？

Answer 1

怎么样：

SELECT 
     p.FirstName,
     p.LastName,
     Count(a.attendance_date) AS CountOfattendance_date,
     First(a.attendance_date) AS FirstOfattendance_date,
     c.total
FROM (
     tblPeople AS p 
INNER JOIN tblEventAttendance AS a ON 
     a.people_id = p.ID) 
INNER JOIN (SELECT people_id, Count (attendance_date) As total
            FROM (
                SELECT DISTINCT people_id,attendance_date
                FROM tblEventAttendance) 
            Group By people_id) AS c ON 
     p.ID = c.people_id
GROUP BY 
     p.ID, c.total;

Answer 2

你能改变吗

B.attendance_date >= FirstOfattendance_date

到

B.attendance_date >= First(A.attendance_date)