oracle 如何在 Hibernate 查询语言中执行左连接？
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How to perform left join in Hibernate Query Language?
提问by karthik.A.M
This is my HQL query, but it isn't working and is throwing an error.
这是我的 HQL 查询，但它不起作用并引发错误。
Hql query:
后台查询：
SELECT
*
FROM
TABLEA A
LEFT JOIN
A.TABLEB B
WHERE
A.COLUMNNAME = B.COLUMNAME
and it causes this error:
它会导致此错误：
org.hibernate.QueryException:
This Query caught Exception. could not resolve property: of TABLEB:TABLEA.
How can I solve this problem? Actually I retrieved a value from more than one table. This query doesn't work with CreateQuery(strQuery).
我怎么解决这个问题？实际上，我从多个表中检索了一个值。此查询不适用于CreateQuery(strQuery).
回答by Joe Taras
In HQLyou can use LEFT JOINonly with linked property in main entity:
在HQL您LEFT JOIN只能与主实体中的链接属性一起使用：
Sample
样本
EntityA has an object entityB of type EntityB so you can
EntityA 有一个 EntityB 类型的对象 entityB，因此您可以
SELECT A FROM EntityA A LEFT JOIN A.entityB B WHERE ...
IF EntityA haven't entityB property but is EntityB have a property entityA, you can't write this:
如果 EntityA 没有 entityB 属性但 EntityB 有一个属性 entityA，则不能这样写：
SELECT A FROM EntityA LEFT JOIN EntityB B WHERE B.entityA = A
because you have an error. This is an Hibernate issue not resolved yet.
因为你有错误。这是一个尚未解决的休眠问题。
