Question

如何编写SQL查询以查找那些共同撰写了一些论文的作者。

架构：

Authors (
    authorID,
    firstName,
);
Papers (
    paperID,
    title,
);
PaperbyAuthor (
    authorID FOREIGN KEY REFERENCES Authors,
    paperID FOREIGN KEY  REFERENCES Papers
);

Answer 1

这将列出所有作者及其PaperID一起撰写论文的作者。

SELECT PA.paperID, GROUP_CONCAT(A.firstName separator ',') FROM PaperbyAuthor PA
INNER JOIN Authors A ON PA.authorID = A.authorID
WHERE paperID IN (SELECT paperID FROM PaperbyAuthor PA
GROUP BY paperID
HAVING COUNT(*) > 1)

如果您需要查看论文标题，也可以使用论文加入表格。

Answer 2

这会给你每一对作者两次：如果约翰和乔共同撰写一篇论文，那么会有参赛作品

CoAuthor1   CoAuthor2   JointPapers 
JOHN        JOE         1
JOE         JOHN        1

代码是：

SELECT
    a1.firstName AS CoAuthor1,
    a2.firstName AS CoAuthor2,
    l.JointPapers
FROM
    (
    SELECT
        pba1.authorID AS CoAuthorID1,
        pba2.authorID AS CoAuthorID2,
        COUNT(*) AS JointPapers
    FROM
        PaperByAuthor AS pba1
    LEFT JOIN
        PaperByAuthor AS pba2
    ON
        pba1.paperID = pba2.paperID
    GROUP BY
        pba1.authorID,
        pba2.authorID
    ) AS l  
LEFT JOIN
    Authors AS a1
ON
    l.CoAuthorID1 = a1.authorID
LEFT JOIN
    Authors AS a2
ON
    l.CoAuthorID2 = a2.authorID

Answer 3

如果您想要共同撰写特定论文的作者，请尝试：

SELECT a.authorID, a.firstName
FROM Authors a
INNER JOIN PaperbyAuthor pa ON pa.authorID = a.authorID
INNER JOIN Papers p ON p.paperID = pa.paperID
WHERE p.paperID = 1000;

将值1000更改为所需纸张的ID。如果要按标题查找论文，请将最后一行更改为：

WHERE p.title = 'The Best Paper';

Answer 4

您只是在寻找作者对吗？

select distinct min(authorID), max(authorID)
from PapersByAuthor pa
group by paperID
having count(authorID) = 2

如何找到所有这些作者一起写了一篇论文？

4 个答案: