我正在尝试将数据库从 sqlite 迁移到 mariaDB(我从未使用过),但我似乎无法解决这个问题!
当我尝试运行它时,我总是得到
"#1060 - Duplicate column name 'id_document'"
这是查询:
SELECT
a.id_document AS id_document,
id_user_associatedDoc,
id_user_creator,
stage,
title,
goldStandardAnnotationManual,
count(content) AS answer_count
FROM
(SELECT *
FROM Document join DocumentProject
ON Document.id_document = DocumentProject.id_document
WHERE DocumentProject.id_project = 2) a
LEFT JOIN
(SELECT *
FROM Annotation
WHERE Annotation.id_project = 2) b
ON a.id_document = b.id_document
GROUP BY a.id_document;
我不明白为什么我会收到此错误!你能帮忙吗?
最佳答案
第一个子查询语法返回两个 id_document 列:
(SELECT *
FROM Document
join DocumentProject
ON Document.id_document = DocumentProject.id_document
WHERE DocumentProject.id_project = 2) a
解决此问题的快速方法:
SELECT
a.id_doc /*Change this column as following*/ AS id_document,
id_user_associatedDoc,
id_user_creator,
stage,
title,
goldStandardAnnotationManual,
count(content) AS answer_count
FROM
(SELECT *, Document.id_document as "id_doc" /*define the first id_document column as a different name*/
FROM Document
join DocumentProject
ON Document.id_document = DocumentProject.id_document
WHERE DocumentProject.id_project = 2) a
LEFT JOIN
(SELECT *
FROM Annotation
WHERE Annotation.id_project = 2) b
ON a.id_document = b.id_document
GROUP BY a.id_document;
您还可以预先定义要在子查询中返回哪一列。示例:
(SELECT Document.id_document, Document.column_2, Document.column_3
FROM Document
join DocumentProject
ON Document.id_document = DocumentProject.id_document
WHERE DocumentProject.id_project = 2) a
这样,您的外部查询应该根据您在子查询中预定义的内容选择 a.id_document,并且不需要从外部查询中更改任何内容。
关于mysql - "Duplicate column name"不应该存在的错误,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54184781/