one-to-one is mainly used for two
tables sharing the same primary key. For foreign key association,
we normally use
many-to-one instead. However, with
one-to-one is able to link up
tables via a foreign key. The above
example can be mapped by
one-to-one as follows:
<hibernate-mapping> <class name="Company" table="Company" > <id name="id" /> <one-to-one name="defaultContactPerson" property-ref="defaultContactPerson" > <formula>id</formula> <formula>1</formula> </many-to-one> </class> <class name="Person" > <id name="id" /> <properties name="defaultContactPerson"> <property name="companyID" /> <property name="defaultFlag" /> </properties> </class> </hibernate-mapping>
formula can be used with a
many-to-many element for a special joining from
relationship table to an entity table, although this is not often
The examples in this article show most of the
formula usage scenarios. When a
evaluation value is needed, the
will appear in the
select part of the resulting SQL
statement. And when a
formula is used for joining, it
appears in the
where part of the resulting SQL statement.
formula expression can use any dialect
of SQL, as long as the target database can support it. As a result,
formula helps achieve fine-grained mapping from data
model to object model without code.
- Sample code for this article.
- Hibernate provides most information about Hibernate ORM.
- Filter Article on TheServerSide for external filter introduction.
- Spring is a very friendly framework and provides integration with Hibernate and other data access tools.
- "Dependency Injection:" A definitive introduction of dependency injection.
- Dependency Injection Basics: An easy-to-understand introduction of dependency injection.
Dai Yifan is a technical consultant for a leading banking solution provider
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