What was the topic of the show on March 15, 2008?
CREATE TABLE "dsds_performances" (
  "date" text,
  "topic_of_the_show" text,
  "song" text,
  "original_artist" text,
  "place_percentage" text
);
SELECT "topic_of_the_show" FROM "dsds_performances" WHERE "date"='march 15, 2008';