Table: swimming_records_2
Columns: event
time
nationality
date
meet
location

Question: What is Date, when Time is "56.49"?
SQL: SELECT "date" FROM swimming_records_2 WHERE "time" = '56.49'

Question: What is Event, when Date is "19 December 2009"?
SQL: SELECT "event" FROM swimming_records_2 WHERE "date" = '19 december 2009'

Question: What is Time, when Meet is "Duel in the Pool", and when Date is "19 December 2009"?
SQL: SELECT "time" FROM swimming_records_2 WHERE "meet" = 'duel in the pool' AND "date" = '19 december 2009'

Question: What is the Location, when Event is "100m Butterfly"?
SQL: SELECT "location" FROM swimming_records_2 WHERE "event" = '100m butterfly'

Question: What is Date, when Meet is "World Championships", when Nationality is "United States", and when Time is "1:46.68"?
SQL: SELECT "date" FROM swimming_records_2 WHERE "meet" = 'world championships' AND "nationality" = 'united states' AND "time" = '1:46.68'

Question: What is Event, when Meet is "World Championships", and when Time is "20.51"?
SQL: SELECT "event" FROM swimming_records_2 WHERE "meet" = 'world championships' AND "time" = '20.51'