Hibernate version: 2.1

I've got a bottom-up situation (I've inherited a database schema that I cannot change) and am wondering how much flexibility I have in my mapping documents when I indicate something like:




and the underlying MySQL column is something like:




Better put, what is the mechanism that determines how the underlying SQL column is converted to the Integer type indicated above? Presumably I can't just specifiy *anything* for the hibernate type, it must have to conform to the underlying SQL columh type somehow.

So I guess my questions are:

* How does Hibernate convert between the types indicated in the mapping file and the underling SQL column types?

* What kind of flexibility do I have here? Can I take that MySQL SMALLINT and map it to an java.lang.Integer? For "reads" this should not be a problem (a mysql smallint fits inside a java.lang.Integer) but what happens during "writes" (when the Integer contains more data than will fit within the smallint)?

* Is there a document that lists the Hibernate types, the corresponding Mysql types, and the conversion behavior?

For direct JDBC use, this document (among others) answers these questions:

[url]
http://java.sun.com/j2se/1.3/docs/guide ... ml#1053867
[/url]

Does a similar document exist for Hibernate. Or perhaps Hibernate is simply using JDBC and the type mappings defined in the JDBC docs are what I should reference?

Thanks much,

- Gary[/code]

Hibernate uses JDBC as the interface to the database so the type mappings, eg, Java -> SQL constraints are detemined by JDBC driver in use.

Excellent. Does Hibernate use JDBC's "SetObject/GetObject" and, thus, offer the type conversions described in 8.9.5 and 8.9.6 of the Sun JDBC document?

http://java.sun.com/j2se/1.3/docs/guide ... ml#1053867

That would be just nifty. I've got a database full of MySQL TINYINT and SMALLINT fields that I'd vastly prefer to map direclty to an java.lang.Integer. If I can just tell Hibernate that the fields map to an Integer and let JDBC deal with the type conversions my life will be much easier.

Can you confirm?

Thanks again,

- gary

Read the documentation, source and check UserType. Its trivial.