如何使用NHibernate为枚举设置默认值？

Given the following tables:

给出以下表格：

create table TypeAccount
(
    AccountTypeID int primary key identity(1,1),
    [Description] varchar(100) not null
)

create table Account
(
    --AccountID char(32) primary key not null,
    AccountID int primary key identity(1,1),
    AccountName varchar(50),
    AccountTypeID int foreign key references TypeAccount(AccountTypeID),
    CreateDate datetime
)
create