Many to many example 1 of 4

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="TstDBConnection.Entities" assembly="TstDBConnection">
  <class name="Product" table="Product">
    <id name="Id" column="Id">
      <generator class="guid.comb"/>
    </id>
    <property name="Name" column="Name"></property>
    <bag name="Orders" generic="true" table="ProductOrder" cascade="save-update">
      <key column="ProductId" />
      <many-to-many column="OrderId" class ="Order" />
    </bag>
  </class>
</hibernate-mapping>

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="TstDBConnection.Entities" assembly="TstDBConnection">
  <class name="Order" table="[Order]">
    <id name="Id" column="Id">
      <generator class="guid.comb"/>
    </id>
    <property name="Name" column="Name"></property>
    <bag name="Products" generic="true" table="ProductOrder" cascade="save-update">
      <key column="OrderId" />
      <many-to-many column="ProductId" class ="Product"/>
    </bag>
  </class>
</hibernate-mapping>

namespace TstDBConnection.Entities
{
    public class Order
    {
        public virtual Guid Id { get; set; }
        public virtual string Name { get; set; }
        public virtual IList<Product> Products { get; set; }
    }
}

namespace TstDBConnection.Entities
{
    public class Product
    {
        public virtual Guid Id { get; set; }
        public virtual string Name { get; set; }
        public virtual IList<Order> Orders { get; set; }
    }
}

        public static void TestMany2Many(ISessionFactory sessionFactory)
        {
            using (ISession session = sessionFactory.OpenSession())
            {
                Product product = new Product() { Name = "A product" };
                Order order = new Order()
                {
                    Products = new List<Product>() { product },
                    Name = "Coffee CupBox"
                };
                var id = session.Save(order);
                session.Flush();
            }
        }

        static void Main(string[] args)
        {
            log4net.Config.XmlConfigurator.Configure(); // log4net
            Configuration configuration = new Configuration();
            configuration.Configure();
            ISessionFactory sessionFactory = configuration.BuildSessionFactory();

            TestMany2Many(sessionFactory);

            sessionFactory.Close();
        }