grails / gorm / mysql /休眠

Question

I have a simples question. I have been trying to learn Grails by my own, and i managed to do a simple application using Grails/Gorm.

1 ) Later, i decided to use Mysql instead of Gorm - i just needed to configure the 'DataSource' and download the driver.

2 )So if i want to use hibernate between both (Grails and MYSQL) like this: http://www.grails.org/doc/latest/guide/15.%20Grails%20and%20Hibernate.html , i need to make an 'hibernate.cfg.xml' file, and specify my mysql database url, user, pw etc .. and i have to map each Class in Grails for MySql columns.

So what is the diference between 1) and 2) ? and what exactly hibernate does. Give examples if possible

PS. Please correct me if i said something wrong, im kinda new to this

Answer 1

I think you are a bit confused here.

GORM is not a database, it is a ORM that maps you Groovy classes to database tables. It uses Hibernate under the covers to achieve this (Hibernate is also an ORM).

The default database Grails uses is an in-memory HSQL DB. If you want to use MySQL instead of that, all you need to do is change the settings in conf/DataSource.groovy.

You don't need to create any Hibernate xml files. That part of the documentation you've linked to is to allow people with existing Hibernate domain models to easily re-use them.

Hope this helps clear things up.

cheers

Lee