CREATE TABLE table_21634 ("Series #" FLOAT, "Season #" FLOAT, "Title" CLOB, "Directed by" CLOB, "Written by" CLOB, "Original air date" CLOB)

On which dates did the episodes directed by TR Babu Subramaniam air?
SELECT "Original air date" FROM table_21634 WHERE "Directed by" = 'TR Babu Subramaniam'
SELECT "Original air date" FROM "table_21634" WHERE "Directed by" = 'TR Babu Subramaniam'