如何使用具有內部選擇案例的NHibernate重新創建SQL語句？

Question

我試圖重新像使用NHibernate標準的SQL語句：

select Range, count(*) from (
    select 
     case 
     when ent.ID between 'A' and 'N' then 'A-M' 
     else 'Other' 
     end as Range 
    from Subject 
) tbl 
group by tbl.Range 

我能夠創造內部的選擇如下：

session.CreateCriteria<Subject>() 
    .SetProjection(
     Projections.Conditional(
     Expression.Between("Name", "A", "N"), 
     Projections.Constant("A-M"), 
     Projections.Constant("Other"))) 
    .List(); 

然而，我無法弄清楚如何將這些結果按行計數分組。

Answer 1

這應該工作...

session.CreateCriteria<Subject>() 
    .SetProjection(
     Projections.ProjectionList() 
      .Add(
      Projections.GroupProperty(
       Projections.Conditional(
        Restrictions.Between("Name", "A", "N"), 
        Projections.Constant("A-M"), 
        Projections.Constant("Other")))) 
     .Add(Projections.RowCount())) 
    .List(); 

...但事實並非如此。所以你可以這樣做：

session.CreateCriteria<Subject>() 
    .SetProjection(
     Projections.ProjectionList() 
     .Add(
      Projections.GroupProperty(
       Projections.SqlProjection(
        @"case 
         when Name between 'A' and 'N' then 'A-M' 
         else 'Other' 
        end as Range", 
        new[] { "Range" }, 
        new[] { TypeFactory.GetStringType(5) }))) 
     .Add(Projections.RowCount())) 
    .List();