R – Excluding some tables from Fluent Nhibernate schema Generation

The SchemaUpdate object provides database schema updating, by apparently generating and executing a series of SQL UPDATE statements (as well as constraint statements) when it's void Execute(bool script, bool doUpdate) function is called. The SchemaUpdate class is in the NHibernate.Tool.hbm2ddl namespace, which can be found in the Nhibernate.dll file.

SchemaUpdate is mentioned in chapter 15 of the nhibernate 1.0.2 toolset guide, here (section 15.1.5).

"The NHibernate FAQ" had (link now expired) a more complete example of how to use SchemaUpdate:

[Test]
public void Update_an_existing_database_schema()
{
    _cfg = new Configuration();
    _cfg.Configure();
    _cfg.AddAssembly(Assembly.LoadFrom("DataLayer.dll"));
    var update = new SchemaUpdate(_cfg);
    update.Execute(true, false);
}

What you're looking for is a of a set of elements, which in standard hbm mapping is:

<set name="Roles" table="UserRoles">
  <key column="UserID" />
  <element column="Role" />
</set>

For Fluent NHibernate you can map this like so:

HasMany<string>(x => x.Roles)
  .AsElement("Role");

You may need to also specify the key name using WithKeyColumn(string).