nhibernate - Which ORM frameworks will build and execute the SQL DDL for you?

Question

Entity Framework Code First will build the database for you if it doesn't exist and structure it based on your mapping objects. I believe Roundhouse will do the same thing with Fluent Mapping files using NHibernate.

Are there any other ORM's (or tools like Roundhouse) that will take care of all your SQL DDL creation and execution?

Answer 1

NHibernate does not need Fluent Mappings to generate database schema. This feature is built into the NHibernate core:

new SchemaExport(_configuration).Execute(false, true, false);

In my experience however this is mostly useful for in-memory integration tests or initial rollouts. Production databases need to be upgraded. If you stick around, then you will need to add and remove columns, tables and foreign keys without affecting data. There is a continuity and versioning aspect to it. NHibernate only knows your current mapping. It does not know for example that 2 months ago you stored your customer first and last name in column called "CustomerName" and then you decided to split this into two columns "FirstName" and "LastName" (which is probably the most primitive change that can be made). NHibernate job is to map your current schema to objects, not to remember data modeling choices from few years ago.

In my experience there is no magic tool that will write upgrade scripts, they have to be written manually or at least reviewed by developer. Tools can provide you a framework for executing these scripts, like RoundhouseE. Scott Allen has an excellent series about 'forward-only, run-once' approach.