Linq: Join on multiple kinds of conditions

Question

I'm trying to join on multiple conditions. The problem is that it is a mix of 'equals' and 'not equals'. This previous answer only works if you want to join on 'equals'.

from p1 in context.Set<PersonList>()
join p2 in context.Set<PersonList>()
on p1.Email equals p2.Email && p1.PersonID != p2.PersonID

How about providing some sample code and what you have tried? — NetMage, Jun 20 '17 at 21:14

NetMage · Answer 1 · 2017-06-26T17:35:22.897

0

Just use where to capture the extra conditions:

from p1 in context.Set<PersonList>()
join p2 in context.Set<PersonList>()
on p1.Email equals p2.Email into p2j
from p2 in p2j.DefaultIfEmpty()
where p2 != null && p1.PersonID != p2.PersonID

edited Jun 26 '17 at 17:35

answered Jun 21 '17 at 20:00

NetMage

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True, but you can't do an outer join with it. – Wouter Jun 22 '17 at 09:56
Your example isn't an outer join. Do you want a left or right outer join? – NetMage Jun 22 '17 at 16:03
Left outer join. – Wouter Jun 26 '17 at 06:40
Changed to left outer join; not testing `PersonID` if `p2` is null, but you can remove that test if you want to find all `p1` missing `p2` as well. – NetMage Jun 26 '17 at 17:36

Linq: Join on multiple kinds of conditions

1 Answers1