CREATE TABLE [dbo].[T_Area](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [AreaName] [nvarchar](50) COLLATE Chinese_PRC_CI_AS NULL,
 CONSTRAINT [PK_T_Area] PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]


CREATE TABLE [dbo].[T_Unit](
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [UnitName] [nvarchar](50) COLLATE Chinese_PRC_CI_AS NULL,
    [AreaID] [int] NULL,
 CONSTRAINT [PK_T_Unit] PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]

namespace Wujy.ModelLibrary.Entity
{
    public class AreaModel
    {
        public virtual int Id { get; set; }
        public virtual string Areaname { get; set; }
        public virtual UnitModel unit { get; set; }
    }
}


namespace Wujy.ModelLibrary.Entity
{
    public class UnitModel
    {
        public virtual int Id { get; set; }
        public virtual string Unitname { get; set; }
        public virtual int? Areaid { get; set; }
        public virtual AreaModel area { get; set; }
    }
}

<hibernate-mapping assembly="Wujy.ModelLibrary" namespace="Wujy.ModelLibrary.Entity" xmlns="urn:nhibernate-mapping-2.2">
  <class name="AreaModel" table="T_Area" lazy="true" >
    <id name="Id" column="ID">
      <generator class="identity" />
    </id>
    <property name="Areaname">
      <column name="AreaName" sql-type="nvarchar" not-null="false" />
    </property>
    <one-to-one name="unit" cascade="all"></one-to-one>
  </class>
</hibernate-mapping>

<hibernate-mapping assembly="Wujy.ModelLibrary" namespace="Wujy.ModelLibrary.Entity" xmlns="urn:nhibernate-mapping-2.2">
  <class name="UnitModel" table="T_Unit" lazy="true" >
    <id name="Id" column="ID">
      <generator class="identity" />
    </id>
    <property name="Unitname">
      <column name="UnitName" sql-type="nvarchar" not-null="false" />
    </property>
    <property name="Areaid">
      <column name="AreaID" sql-type="int" not-null="false" />
    </property>
    <one-to-one name="area" cascade="all"></one-to-one>
  </class>
</hibernate-mapping>

        protected void Button1_Click(object sender, EventArgs e)
        {
            AreaModel model = new AreaModel();
            model.Areaname = "厦门";
            AreaBll.Add(model);
            Response.Write("成功");
        }

        protected void Button2_Click(object sender, EventArgs e)
        {
            UnitModel model = new UnitModel();
            model.Unitname = "软件园";
            model.Areaid = 1;
            UnitBll.Add(model);
            Response.Write("成功");
        }

        protected void Button3_Click(object sender, EventArgs e)
        {
            UnitModel model = UnitBll.findById(1);
            Response.Write(model.area.Areaname + "|" + model.Areaid + "|" + model.Unitname);

            AreaModel areamodel = AreaBll.findById(1);
            Response.Write("<br/>"+areamodel.unit.Unitname);
        }

        protected void Button4_Click(object sender, EventArgs e)
        {
            UnitModel model = UnitBll.findById(1);
            UnitBll.Remove(model);
            Response.Write("成功");
        }

            UnitModel model = UnitBll.findById(1);
            UnitBll.Remove(model);
            Response.Write("成功");

或

            AreaModel model = AreaBll.findById(1);
            AreaBll.Remove(model);
            Response.Write("成功");

<one-to-one
        name="PropertyName"                               
        class="ClassName"                                  
        cascade="all|none|save-update|delete"              
        constrained="true|false"                           
        fetch="join|select"                                
        property-ref="PropertyNameFromAssociatedClass"     
        access="field|property|nosetter|ClassName"         
/>  

(1)  name: 属性的名字。 
(2)  class (可选 - 默认是通过反射得到的属性类型)：被关联的类的名字。 
(3)  cascade(级联) (可选) 表明操作是否从父对象级联到被关联的对象。 
(4)  constrained(约束) (可选) 表明该类对应的表对应的数据库表，和被关联的对象所对应的数据库表之间，通过一个外键引用对主键进行约束。 这个选项影响Save()
        和Delete()在级联执行时的先后顺序以及 决定该关联能否被委托(也在schema export tool中被使用).  
(5)  fetch (可选 - 默认设置为select): 在外连接抓取或者序列选择抓取选择其一. 
(6)  property-ref: (可选) 指定关联类的属性名，这个属性将会和本类的主键相对应。如果没有指定，会使用对方关联类的主键。 
(7)  access (可选 - 默认是 property): NHibernate用来访问属性的策略。