Question: Who directed the episode that originally aired on March 18, 1988?
SQL: SELECT "Directed by" FROM "1-20967430-4" WHERE "Original air date" = 'March 18, 1988';

Question: What is the episode number in the series for "Graduation" that was directed by Don Corvan?
SQL: SELECT MIN("Ep.") FROM "1-20967430-4" WHERE "Directed by" = 'Don Corvan' AND "Title" = '"Graduation"';

Question: What was the name of the episode that aired originally on March 11, 1988?
SQL: SELECT "Title" FROM "1-20967430-4" WHERE "Original air date" = 'March 11, 1988';

Question: What is the production code of the episode written by Jack Carrerrow?
SQL: SELECT "Prod. Code" FROM "1-20967430-4" WHERE "Written by" = 'Jack Carrerrow';

Question: How many episodes had a production code of 5M13?
SQL: SELECT COUNT("Ep.") FROM "1-20967430-4" WHERE "Prod. Code" = '5M13';