JPA-左联接2个表而没有关联 [英] JPA - left join 2 tables without association

问题描述

我有 2个表/实体，且没有关联. 我可以在JPA中进行 交叉联接

I have 2 tables/entities with no association. I can go for cross joins in JPA

FROM A as a, B as b WHERE b.col1=a.col1

如何执行左联接?

How Can I perform a left-join?

我想要A中的所有值，并在可能的情况下用B值填充它们，而在没有B的地方保留NULL.

I want all values from A and fill them up with B values where possible and leave NULL where there is no B.

不起作用:

FROM A as a LEFT JOIN B as b WHERE b.col1=a.col1

希望加入的路径！

Path expected for join!

无效路径:"b.col1"

Invalid path: 'b.col1'

推荐答案

对于JPA，可以通过以下查询来实现:

This is possible with JPA with following query:

FROM A as a, B as b WHERE b.col1=a.col1 OR b.col1 IS NULL

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