Question

linq only supports inner join, how to do left join using linq query.
also linq supports join only using ‘equals’ keyword but is it possible to use other join conditions?

Answer 1

Like this:

from tableA in dataContext.TableA
from tableB in dataContext.TableB.Where(b => b.Id == a.TableBId).DefaultIfEmpty() 
select new { tableA, tableB };

Then you can change the condition in the Where clause to use whatever operator.
Using anything else other than equals in the join operator is not possible.

There are other ways to do it, like: http://www.hookedonlinq.com/OuterJoinSample.ashx