删除表中所有在另一个表中没有引用的记录 [英] Delete all records in table which have no reference in another table
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问题描述
我有一个名为 Document
的表格.
I have a table which is called Document
.
文档:
id int
docuid int
doc blob
然后我有两个引用表
AppRequiredDocuments:
id int
appid int
docid int -> references document -> id
应用文档:
id int
appid int
docid int -> references document -> id
由于非常旧的迁移,文档表中的孤立项目必须引用其他表中的项目.如何仅删除AppDocuments
或AppRequriedDocuments
中未引用的文档表中的文档?
I have due to an very old migration orphaned items in the document table which have to references in the other tables. How can I delete only the documents in the document table which are not referenced in AppDocuments
or AppRequriedDocuments
?
推荐答案
您可以使用 NOT EXISTS
来查找和删除这些项目:
You can use NOT EXISTS
to find and delete those items:
delete from document d
where not exists (select 1 from AppRequiredDocuments a where a.docid = d.id);
and not exists (select 1 from AppDocuments a where a.docid = d.id);
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