Table: world_weightlifting_2005
Columns: rank
nation
gold
silver
bronze
total

Question: what is the highest gold when the rank is 12 for the nation vietnam?
SQL: SELECT MAX("gold") FROM world_weightlifting_2005 WHERE "rank" = '12' AND "nation" = 'vietnam'

Question: what is the total when the rank is 4?
SQL: SELECT "total" FROM world_weightlifting_2005 WHERE "rank" = '4'

Question: what is the nation when the gold is 1 and bronze is larger than 0?
SQL: SELECT "nation" FROM world_weightlifting_2005 WHERE "gold" = 1 AND "bronze" > 0