annotated_self = Showing.objects.filter(pk=8).annotate( num=Sum('billig_showing__ticket_groups__num'), num_sold=Sum('billig_showing__ticket_groups__num_sold') )

gistfile1.sql

SELECT "event_showing"."id", "event_showing"."event_id", "event_showing"."billig_showing_id", 
"event_showing"."uka_showing_id", "event_showing"."publish_time", "event_showing"."place", 
"event_showing"."free", "event_showing"."canceled", "event_showing"."entrance_id", 
SUM("billig_ticket_group"."num") AS "num", 
SUM("billig_ticket_group"."num_sold") AS "num_sold" 
FROM "event_showing" 
LEFT OUTER JOIN "billig_event" ON ("event_showing"."billig_showing_id" = "billig_event"."event") 
LEFT OUTER JOIN "event_ukashowing" ON ("event_showing"."uka_showing_id" = "event_ukashowing"."id") 
LEFT OUTER JOIN "billig_ticket_group" ON ("billig_event"."event" = "billig_ticket_group"."event") 
WHERE "event_showing"."id" = 8  
GROUP BY "event_showing"."id", "event_showing"."event_id", "event_showing"."billig_showing_id", "event_showing"."uka_showing_id", "event_showing"."publish_time", "event_showing"."place", "event_showing"."free", "event_showing"."canceled", "event_showing"."entrance_id", "billig_event"."event_time", "event_ukashowing"."date" 
ORDER BY "billig_event"."event_time" ASC, "event_ukashowing"."date" ASC