Aggregating records when Salesforce query returns multiple records

[Anonymous]

So I have a Salesforce query that looks like this:

SELECT Id

, r_physician_id__r.LastName

FROM

     blah, blah, blah,

The field in the select statement is a lookup relationship in Salesforce.  In the SF Developers console the results look like this:

However when I retrieve the same results via the SF Connector in QS Enterprise I get this:

I suspect the reason for the difference is that the lookup relationship is SF is doing sort of an outer join resulting in one null record and one with the data I am after.  I don't know if there is anything I can do to the SF query to make it work right.

So I was trying to correct for this in the load script and I cannot figure out how to merge the records.  Here is what I am trying:

Load

r_reeg__c.Id AS peer_id

    , MaxString(r_reeg__c.r_physician_id__r.LastName) AS physician_lastname

    WHERE r_reeg__c.Id <> Null()

    GROUP BY

    r_reeg__c.Id    

    ;

and here is what I get:

I have tried all of the string aggregation functions to no avail.

How can I aggregate the data so as to eliminate the null values?

Any help would be greatly appreciated.