Linq to NHibernate返回的结果与HQL不同？

Question

I have this basic entity setup:

public class Instrument
{
    public virtual int Id { get; set; }
    public virtual Guid? InstrumentGuid { get; set; }
    public virtual string FIPSCode { get; set; }
    public virtual IList Names {get; set;}
}

public class Name
{
    public virtual int Id {get; set;}
    public virtual string Name {get; set;}
    public virtual Instrument Instrument {get; set;}
}

Mappings:

public class InstrumentMap: ClassMap<Instrument>
{
    public InstrumentMap()
    {
        Id(x => x.Id);
        Map(x => x.InstrumentGuid).Not.Nullable();
        Map(x => x.FIPSCode).Not.Nullable();
        HasMany(x => x.Names).Casecade.All;
    }
}

public class NameMap : ClassMap<Name>
{
    public NameMap()
    {
        Id(x => x.Id);
        Map(x => x.Name);
        References(x => x.Instrument);
    }
}

So why is it that when I do these two queries do I get different results?

var namelist = from name in Session.Linq()
    where name.Instrument.Id == 1
    select name;

I get 3 results, 2 where Instrument.Id = 1 and 1 where Instrument.Id = 4 vs:

var querystr = "select name From Name as name where name.Instrument.Id = 1";
var hqlresult = Session.CreateQuery(querystr).List();

This gets only the 2 results where Instrument.Id = 1.

Could someone explain where the Id = 4 is coming from in the Linq query, or is NHibernate.Linq not quite stable yet? Thanks!

Answer 1

This sounds like a bug in the linq provider you use. The linq provider you use comes from NHibernate.Contrib. This provider is based on the criteria api. This api might generate different sql than hql. What is the sql created by both of the queries?

In the NHibernate trunk is a new linq provider based on hql. This linq provider will generate the same sql as hql. I moved from the old to the new provider in an application I currently work on. It seams to have more functionality than the old one, but it is still unfinished.

Answer 2

Well I enabled ShowSql on the Sqllite provider (That I'm using for testing), and found that it is creating comperable code for each select.

For some reason, the Linq provider only (both with 2.0 and 3.0 syntax leaves the last item in the repository, that is not a part of the sql query. I recreated the SQL through sqlite3.exe and the output between the two was the same. Oh and it only happens for the Id fields. When I referenced a different field (guid) and used that for the where clause = the results were accurate between Linq and HQL!

So the answer is it's not supposed to I believe, and is a bug. Thanks for all the help - and when I get a chance I will try the new provider, just can't right now on the beta version of our product.