我们可以为 ORM 使用用户定义的（非标量）SQL 类型吗？

Question

I'm wondering if its possible to do ORM using SQL.2003 object types (aka STRUCTs, aka non-scalar types).

The idea behind that is to avoid the "n+1 selects" problem by retrieving complete objects directly from the database. Sort of eager "FetchMode.JOIN", but in the database .

Are there any ORM frameworks fpor Java or.Net which support SQL object types at all?

At least JDBC has the getObject method and I've also found an example of user-defined types in ADO.Net

As an Oracle developer, I may be biased towards database-centric approaches and I also didn't use ORM before. But Oracle features Object Views which let you compose objects from several relational tables. I bet these could be magnitudes faster than pulling all those single records out of the database, let alone issuing n+1 selects.

Answer 1

I am the developer of jOOQ , and I am striving to make jOOQ exactly what you need. jOOQ currently supports any of these Oracle features:

• All types of SQL constructs, including nested selects, aliasing, union operations, etc
• Stored procedures and functions
• Packages
• VARRAY types (mapped to Java arrays)
• UDT types (mapped to Java objects)
• combinations thereof

More support will be added in the near future, for advanced Oracle concepts such as

• TABLE types
• CURSOR, REF CURSOR types
• Other collection types

Object views are currently not supported in the way you described, but I'll clearly put them on the roadmap.

See more on http://www.jooq.org