Question

Can anybody tell me how I would get the records in the first statement that are not in the second statement (see below)?

from or in TblOrganisations
where or.OrgType == 2
select or.PkOrgID

Second query:

from o in TblOrganisations
 join m in LuMetricSites
 on o.PkOrgID equals m.FkSiteID
 orderby m.SiteOrder
 select o.PkOrgID

Answer 1

Do you need the whole records, or just the IDs? The IDs are easy…

var ids = firstQuery.Except(secondQuery);

EDIT: Okay, if you can’t do that, you’ll need something like:

var secondQuery = ...; // As you've already got it

var query = from or in TblOrganisations
            where or.OrgType == 2
            where !secondQuery.Contains(or.PkOrgID)
            select ...;

Check the SQL it produces, but I think it should do the right thing. Note that there’s no point in performing any ordering in the second query – or even the join against TblOrganisations. In other words, you could use:

var query = from or in TblOrganisations
            where or.OrgType == 2
            where !LuMetricSites.Select(m => m.FkSiteID).Contains(or.PkOrgID)
            select ...;