<?xml version="1.0"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Accounting" assembly="Accounting">
  < class  name="goodsL" table="goods@orcl.testdb">
    <id name="id" column="id" type="int">
      <generator  class ="sequence">
        <param name="sequence">goods_seq</param>
      </generator>
    </id>
    <property name="name"/>
    <property name="articul"/>
    <property name="vendor_articul"/>
    <property name="location" type="integer"/>
    <property name="is_sold"/>
    <property name="was_excluded"/>
    <property name="labeled_cost"/>
    <property name="goods_type"/>
    <property name="countOverType" 
              formula="(select count(*) from goods s where s.goods_type = goods_type 
                    and s.location = location and s.is_sold = 0 and s.was_excluded = 0 and s.labeled_cost = labeled_cost)"/>
  </ class >
</hibernate-mapping>

goodsL goods = (goodsL)session.CreateQuery("select m from goodsL as m where m.articul = '"+art+"'").List()[ 0 ];

session.FlushMode = FlushMode.Commit;