CREATE TABLE table_28173 ("No." FLOAT, "Title" CLOB, "Directed by" CLOB, "Written by" CLOB, "Original air date" CLOB, "Production code" CLOB, "U.S. viewers  ( million ) " CLOB)

What was the production code of the episode written by Anthony Sparks?
SELECT "Production code" FROM table_28173 WHERE "Written by" = 'Anthony Sparks'
SELECT "Production code" FROM "table_28173" WHERE "Written by" = 'Anthony Sparks'