Table: historical_aircraft_switzerland
Columns: type
registration
design
construction
service
construction_date
conformity_to_original_design
interest
number_existing_in_switzerland
number_existing_worldwide
status

Question: What are all types where registration is HB-OPU?
SQL: SELECT "type" FROM historical_aircraft_switzerland WHERE "registration" = 'HB-OPU'

Question: What is every registration for the type of T 6 G?
SQL: SELECT "registration" FROM historical_aircraft_switzerland WHERE "type" = 'T 6 G'

Question: What is every construction date for the registration of HB-HOS?
SQL: SELECT "construction_date" FROM historical_aircraft_switzerland WHERE "registration" = 'HB-HOS'

Question: What is every conformity to original design if the construction date is after 1945 and registration is HB-SAE?
SQL: SELECT "conformity_to_original_design" FROM historical_aircraft_switzerland WHERE "construction_date" = 'After 1945' AND "registration" = 'HB-SAE'

Question: What is every conformity to original design if registration is HB-DAI?
SQL: SELECT "conformity_to_original_design" FROM historical_aircraft_switzerland WHERE "registration" = 'HB-DAI'