CREATE TABLE table_31212 ("Episode" TEXT, "Theme / Date" TEXT, "Song title" TEXT, "Original performer" TEXT, "Result  ( Placement ) " TEXT)

What is the episode when the original performaer is diana ross?
SELECT "Episode" FROM table_31212 WHERE "Original performer" = 'Diana Ross'
SELECT "Episode" FROM "table_31212" WHERE "Original performer" = 'Diana Ross'