พื้นที่ที่ถูกเผาทั้งหมดจนถึงปัจจุบันคือเท่าไร?ไม่จำเป็นต้องใช้โต๊ะทั้งหมด
What is the total area that has been burned until now?It is not neccessary to use all the tables.
 fires:  fire_year [ number]  discovery_date [ number]  discovery_doy [ number]  discovery_time [ text]  stat_cause_code [ number]  stat_cause_descr [ text]  cont_date [ text]  cont_doy [ text]  cont_time [ text]  fire_size [ number]  fire_size_class [ text]  latitude [ number]  longitude [ number]  owner_code [ number]  owner_descr [ text]  state [ text]  county [ text]  fips_code [ text]  fips_name [ text] 
SELECT SUM(fire_size) FROM fires