NHibernate过滤器用于自联接表

Question

什么是NHibernate过滤器与此SQL查询具有相同的结果：

SELECT A.Id as ItemId, A.column1 as ItemTitle, A.ListId as ItemListId,
B.Id as LookupItemId, B.Value as LookupItemValue, B.ListId as LookupItemListId
FROM MyTable A LEFT JOIN MyTable B ON B.Id = A.LookupId     
WHERE A.ListId = 'EmployeeListGuid'
AND (B.ListId='EmployeerListGuid' OR B.Id IS NULL)    

Answer 1

首先，为实体属性创建别名，这将LEFT JOIN我们的表自我：

criteria.CreateAlias("LookupItem", "B", JoinType.LeftOuterJoin);

然后，我们可以在条件中使用此别名：

critera.Add(Restrictions.Eq("ListId", "EmployeeListGuid"));    
critera.Add(
    Restrictions
      .Or(
        Restrictions.Eq("B.ListId", "EmployeerListGuid"), 
        Restrictions.IsNull("B.Id")));