Question

我有以下查询：

select AP.paper_id as id, 
concat(A.organization, A.country)as org, 
group_concat(SUBSTR(first_name, 1, 1), '. ', last_name SEPARATOR ', ') as initial
                from authors A
                                inner join authors__papers AP ON A.author_id = AP.author_id 
                                join tmp_orgs ORGS ON ORGS.paper_id = AP.paper_id 
                                where ORGS.organization=A.organization AND
                                AP.is_contact_author < 1
                                group by A.organization, AP.paper_id
                order by AP.paper_id, idx

它将数据输出到：

id     org   initial
1001   org1  J. Doe
1001   org1  J.Smith
1003   org2  A. Doe 
1004   org3  A. Smith
1004   org3  B. Doe
1006   org4  B. Smith
1007   org5  C. Doe

我需要的是第4列，它是按paper_id分组的所有组织的计数，因此结果如下：

id     org   initial   org_count
1001   org1  J. Doe    2
1001   org1  J.Smith   2 
1003   org2  A. Doe    1
1004   org3  A. Smith  2
1004   org3  B. Doe    2
1006   org4  B. Smith  1
1007   org5  C. Doe    1

我厌倦了添加子查询：

（SELECT COUNT（DISTINCT（组织））作为来自作者的dcnt A INNER JOIN authors__papers AP on AP.author_id = A.author_id其中AP.is_contact_author＆lt; 1 AND paper_id = ??? GROUP BY paper_id）as org_count

...但是无法弄清楚如何为每一行指定paper_id（上面的查询中的???。并且最好将它作为select中的连接或列，或者它真的重要吗？我不是一个真正的SQL人，但需要它，因为我正在为某人填写。感谢任何帮助！

Answer 1

你快到了，试试这个：

SELECT 
    AP.paper_id AS id, 
    CONCAT(A.organization, A.country) AS org, 
    GROUP_CONCAT(SUBSTR(first_name, 1, 1), '. ', last_name SEPARATOR ', ') AS initial,
    (
        SELECT COUNT(DISTINCT(organization)) AS dcnt
        FROM authors t1
        INNER JOIN authors__papers t2 ON t2.author_id = t1.author_id
        -- INNER JOIN tmp_orgs t3 ON t3.paper_id = t2.paper_id AND t3.organization = t1.organization 
        WHERE t2.is_contact_author < 1 
    ) AS org_count
FROM authors A
INNER JOIN authors__papers AP ON A.author_id = AP.author_id
INNER JOIN tmp_orgs ORGS ON ORGS.paper_id = AP.paper_id
WHERE ORGS.organization = A.organization 
AND AP.is_contact_author < 1
GROUP BY A.organization, AP.paper_id
ORDER BY AP.paper_id, idx

MySQL COUNT ???帮助查询

1 个答案: