CREATE TABLE table_2618152_1 (production_code VARCHAR2, original_air_date VARCHAR2)

The episode with the original air date January 6, 1999, has what production code?
SELECT production_code FROM table_2618152_1 WHERE original_air_date = "January 6, 1999"
SELECT "production_code" FROM "table_2618152_1" WHERE "January 6, 1999" = "original_air_date"