PID
、RID
中的 Activity
形成其复合 PK,每个分别对应于 Publication
和 Researcher
表的 FK
对于每位至少发表过 2 篇论文的研究人员,检索他们自 2000 年以来的所有论文
SELECT PID, RID
FROM Activity
WHERE RID IN (SELECT RID
FROM Activity
GROUP BY RID
HAVING COUNT(RID) >= 2)
如何按出版年份过滤此中期结果?
答案 0 :(得分:0)
您需要加入publications
。使用您的方法:
SELECT a.PID, a.RID
FROM Activity a JOIN
Publications p
ON p.ID = a.PID
WHERE p.year >= 2000 AND
a.RID IN (SELECT a2.RID
FROM Activity a2
GROUP BY a2.RID
HAVING COUNT(*) >= 2
) ;