CREATE TABLE table_27989 ("Series #" FLOAT, "Episode title" CLOB, "Directed by" CLOB, "Written by" CLOB, "Original air date" CLOB, "Prod. code" FLOAT)

Who directed the episode with the production code 10?
SELECT "Directed by" FROM table_27989 WHERE "Prod. code" = '10'
SELECT "Directed by" FROM "table_27989" WHERE "Prod. code" = '10'