Table: world_taekwondo_championships_2005
Columns: rank
nation
gold
silver
bronze
total

Question: How many Silver medals for the Nation of Turkey with a Total of less than 2?
SQL: SELECT SUM("silver") FROM world_taekwondo_championships_2005 WHERE "nation" = 'turkey' AND "total" < 2

Question: How many Gold for the Nation in Rank 15 with 0 Silver?
SQL: SELECT MAX("gold") FROM world_taekwondo_championships_2005 WHERE "rank" = '15' AND "silver" > 0