CREATE TABLE table_12159115_2 (original_air_date VARCHAR2, production_code VARCHAR2)

What's the original air date of the episode with production code 2T6719?
SELECT original_air_date FROM table_12159115_2 WHERE production_code = "2T6719"
SELECT "original_air_date" FROM "table_12159115_2" WHERE "2T6719" = "production_code"