which subsidiary of thai airways serves both chiang mai international airport and chiang mai international airport ?
select distinct var_uri where brack_open dbr_Thai_Airways dbo_subsidiary var_uri sep_dot var_uri dbo_targetAirport dbr_Chiang_Mai_International_Airport sep_dot var_uri dbo_targetAirport dbr_Chiang_Mai_International_Airport sep_dot brack_close