CREATE TABLE table_24023 ("Ep." FLOAT, "Season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Prod. Code" TEXT)

Who directed the episode that originally aired on March 18, 1988?
SELECT "Directed by" FROM table_24023 WHERE "Original air date" = 'March 18, 1988'
SELECT "Directed by" FROM "table_24023" WHERE "Original air date" = 'March 18, 1988'