I know how I'd solve this in SQL, but how to solve within Yellowfin? It doesn't seem you accept an 'is null' operator.
Using 3 example fields, 1 of which can accept nulls. The following join works in SQL.
select * from
a.xx left outer join b. xx
a.[ENTITYID] = b.[ENTITYID]
AND a.[System Project ID] = b.[System Project ID]
AND (a.[System Enquiry ID] = b.[System Enquiry ID] or a.[System Enquiry ID] is null and b.[System Enquiry ID] is null)
However now I must rebuild any reports from scratch to point towards this new View.
Is there anything on your dev backlog to add the ability to write table joins with more flexibility? Adding an new operator 'is null' would allow what I've written in the OP.