Column name 'guid' appears more than once in the result column list

Hello.
I've got a error message: "Column name 'guid' appears more than once in the result column list."
during insert a new row database operation.


My database tables are:

Table named "poi"
with fields:
- guid (PK, uniqueidentifier, not null)
- anydata(nvarchar(50), null)

Table named "attractions"
with fields:
- guid (PK, FK, uniqueidentifier, not null)
- openhours (nvarchar(50), null)
- attractiveness (smallint, null)

"poi" table key is:
- PK_object

"attractions" table keys are:
- PK_attractions
- relationship named FK_attractions_poi where Primary key table is poi.guid
and reign key table is attractions.guid.


I'm trying to do a insert a new row database operation, by C# code:


string s_anydata = "anydata";
short i_atractiveness = 0;
string s_openhours = "09:00 - 10:00";

using (AtrakcjeUnitOfWork uow = Repository.Context.CreateUnitOfWork())
{    
    Poi poi = new Poi();
    Attraction attraction = new Attraction();

    poi.Anydata = s_anydata;
        uow.Add(poi);
 
    attraction.Gu = poi;   //this is Lightspeed OneToManyAssociation (for attraction & poi)
    attraction.Attractiveness = i_atractiveness;
    attraction.Openhours = s_openhours;
                    
        uow.Add(attraction);    
    uow.SaveChanges();
}


Why is there a message "Column name 'guid' appears more than once in the result column list.",
and what I should to do ?

Greetings

This occurs because the guid column is being mapped to both the Id property and the foreign key property.

LightSpeed doesn't really handle the scenario where Ids are also foreign keys, because it expects to be able to allocate Ids itself: that is, in LightSpeed, PKs are opaque and have no business meaning.  If you control the database, you should split the attractions.guid column into an ID column (which will contain arbitrary GUIDs acting as IDs) and a PoiID column (which will contain FKs into the Poi table, i.e. the current contents of the column).

If you do not control the database, you will need to remove the association between Attraction and Poi, and instead create manual traversal methods that use the Id to perform a query.  See http://www.mindscape.co.nz/forums/Thread.aspx?ThreadID=2447 for an example of how to do this.