what's the singles w-l for kim doo-hwan
CREATE TABLE "squad_members" (
  "player" text,
  "years_played" text,
  "total_w_l" text,
  "singles_w_l" text,
  "doubles_w_l" text
);
SELECT "singles_w_l" FROM "squad_members" WHERE "player"='Kim Doo-Hwan';