CREATE TABLE "classification_leadership" (
  "stage" real,
  "winner" text,
  "general_classification" text,
  "points_classification" text,
  "mountains_classification" text,
  "young_rider_classification" text
);

Question: When 19 is the stage who is the points classification?
SQL: SELECT "points_classification" FROM "classification_leadership" WHERE "stage"=19;

Question: When thomas löfkvist is the  young rider classification and alessandro petacchi is the points classification who are the general classifications? 
SQL: SELECT "general_classification" FROM "classification_leadership" WHERE "points_classification"='Alessandro Petacchi' AND "young_rider_classification"='Thomas Löfkvist';

Question: When  thomas löfkvist is the general classification who is the winner?
SQL: SELECT "winner" FROM "classification_leadership" WHERE "general_classification"='Thomas Löfkvist';

Question: When philippe gilbert is the winner who is the points classification?
SQL: SELECT "points_classification" FROM "classification_leadership" WHERE "winner"='Philippe Gilbert';

Question: When danilo di luca is the winner who is the general classification? 
SQL: SELECT "general_classification" FROM "classification_leadership" WHERE "winner"='Danilo Di Luca';