What kind of D.C. has Races smaller than 20, and Points larger than 0, and Drivers of christian vietoris, and Wins of 1?
CREATE TABLE "gp2_series" (
  "year" real,
  "drivers" text,
  "races" real,
  "wins" real,
  "poles" real,
  "f_l" real,
  "points" real,
  "d_c" text,
  "t_c" text
);
SELECT "d_c" FROM "gp2_series" WHERE "races"<20 AND "points">0 AND "drivers"='christian vietoris' AND "wins"=1;