need explanation about a linq query

[Tony Johansson]

Hello!

I just have some question about this linq query.
I have never used this into that is used in this query so I wonder what does
it do here ?
If this into was skipped here what would the difference be ?

var resultMappings =
from wsr in ccrFormObj.myWorksheetRowList
join wsrcm in ccrFormObj.commandMappingList
on wsr.ID equals wsrcm.WorksheetRowID
join wsrpm in ccrFormObj.parameterMappingList
on wsrcm.ID equals wsrpm.CommandMappingObjID
into gj
from subparam in gj.DefaultIfEmpty()
where wsr.WorksheetID == worksheetID
select new
{
wsrow = Convert.ToInt32(wsr.ID),
command = wsrcm.Name,
parametername = (subparam == null ? String.Empty :
subparam.Name)
};

//Tony

 

[Tony Johansson]

Hello!

Can you also explain what does it mean with this DefaultIfEmpty ?

//Tony

 

[rhaazy]

The into statement is inserting the results of the linq query into
temporary storage.
The DefaultEmpty is something that helps handle the case of null value
so you dont get an exception.