NULL Value in DAX statement

Hi,

I would like to add null values to the results_table below. Could anyone please advise me how to do that?

Results_Table =
SELECTCOLUMNS(
GENERATE(
'Table1';
FILTER(
'Table2';
'Table1'[bpf_msevtmgt_eventid] = 'Table2'[pdg_event])
) ;
"SeminarName";[Seminar Name];"SeminarStartDatum";[SeminarStartDate];"Priority";Table2[prioritycode_display];"Phase";[Phase];"OpportunityName";Table2[name];"OpportunityCreatedDate";Table2[createdon]
)

Thanks