What is the former school of the player from Detroit, MI?
CREATE TABLE "roster" (
  "num" real,
  "name" text,
  "position" text,
  "height" text,
  "weight" real,
  "year" text,
  "former_school" text,
  "hometown" text
);
SELECT "former_school" FROM "roster" WHERE "hometown"='Detroit, MI';