SQL查询 - 动态查询子

我有麻烦试图创建一个查询：SQL查询 - 动态查询子

选择谁没有完成所有同行评审的某一周的所有学生。

背景：每周，每个学生必须同行评审同一组中的同龄人。

每个组都可以是不同的大小，这是我遇到的问题。

这是我目前的测试数据：

peer review table

student table

表1：同行评议表
表2：学生表。

这是我的初始查询，根据他们所做的同行评议的数量对所有学生进行分组。我现在需要检查，如果count(*)小于组的大小为每个学生：

SELECT * 
FROM peerreview 
RIGHT JOIN student 
ON student. studentID = peerreview.reviewer 
WHERE week = 11 
GROUP BY studentID 
HAVING Count(*) < ????

来源

2012-05-28 dgamma3

的 '阿凡周= 11' 位有效地把你的右连接成一个INNER JOIN。 –

只是给出d表的列名和普通的id b/w他们。\ – Addicted

下面的查询将返回已审核了所有的学生在同一组的学生。

SELECT a.reviewer, 
     a.groupid 
FROM (SELECT student2.studentID AS reviewer, 
       student1.groupid, 
       Count(*)   AS cnt 
     FROM student student1 
       INNER JOIN peerreview 
         ON student1.studentID = peerreview.reviewee 
       INNER JOIN STUDENT STUDENT2 
         ON student2.studentID = peerreview.reviewer 
     WHERE student2.groupid = student2.groupid 
       AND peerreview.week = 11 
     GROUP BY student1.groupid, 
        student2.studentID) a 
     INNER JOIN (SELECT groupid, 
          Count(*) - 1 AS cnt 
        FROM student 
        GROUP BY groupid) b 
       ON a.groupid = b.groupid 
        AND a.cnt = b.cnt

See SqlFiddle

来源

2012-05-28 09:55:44

mysql会抛出一个错误：表'student2'不存在 – dgamma3

现在验证sql。 –

很好，你能解释一下student2是什么吗？ – dgamma3

Select S.StudentId As Reviewer 
    , S1.StudentId As StudentYetToBeReviewed 
    , Weeks.WeekNum 
From Student As S 
    Join Student As S1 
     On S1.GroupId = S.GroupId 
      And S1.StudentId <> S.StudentId 
    Cross Join (
       Select 7 As WeekNum 
       Union All Select 11 
       ) As Weeks 
Where Not Exists (
        Select 1 
        From PeerReview As P1 
        Where P1.reviewee = S1.StudentId 
         And P1.Week = Weeks.WeekNum 
        ) 
Order By WeekNum, reviewer

这为您提供一个清单，按周，审稿人，他们需要审查的人。在真正的解决方案中，您可能希望用周数的明确列表来替换交叉连接周数，在这些周内应该进行审查。

SQL Fiddle版本

来源

2012-05-28 10:18:24 Thomas

select distinct s1.* 
    from student s1 inner join student s2 on s1.groupId = s2.groupeId 
       left join peerreview pr on pr.revieweer = s1.studentId 
        and pr.reviewee = s2.studentId 
    where pr.Week = ? and pr.revieweer is null and s1.studentId <> s2.studentId

来源

2012-05-28 10:54:41

SQL查询 - 动态查询子

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