How many combination classifications have the winner as Erik Zabel and a points classification as Alessandro Petacchi
CREATE TABLE "jersey_progress" (
  "stage" real,
  "winner" text,
  "general_classification" text,
  "points_classification" text,
  "mountains_classification" text,
  "combination_classification" text,
  "team_classification" text
);
SELECT COUNT("combination_classification") FROM "jersey_progress" WHERE "points_classification"='Alessandro Petacchi' AND "winner"='Erik Zabel';