# Database Mapping Usage

Domain classes in Grails by default dictate the way they are mapped to the database using sensible defaults. You can customize these with the ORM Mapping DSL. For example create a `Book` domain:

    grails create-domain-class Book

And then you can use the `mapping` block to customize the ORM mapping behavior.

    class Book {
    	String title
    	Date releaseDate
    	Author author	static mapping = {
    		table "books"
    		author column:"auth_id"
    	}
    }

Refer to the user guide section on ORM Mapping for more information.

# Global Database Mapping

You can configure mapping globally in `grails-app/conf/Config.groovy` as follows:

    grails.gorm.default.mapping = {
       cache true
       id generator:'sequence'
       'user-type'( type:org.hibernate.type.YesNoType, class:Boolean )
    }