CREATE TABLE table_name_83 (Id VARCHAR2)

Which 2009 has a 2006 of A, and a 2011 of sf?
SELECT 2009 FROM table_name_83 WHERE 2006 = "a" AND 2011 = "sf"
SELECT 2009 FROM "table_name_83" WHERE "a" = 2006 AND "sf" = 2011