CREATE TABLE "past_winners" (
  "year" real,
  "mens_singles" text,
  "womens_singles" text,
  "mens_doubles" text,
  "womens_doubles" text,
  "mixed_doubles" text
);

Question: How many mens doubles when womens doubles is catrine bengtsson margit borg?
SQL: SELECT COUNT("mens_doubles") FROM "past_winners" WHERE "womens_doubles"='Catrine Bengtsson Margit Borg';

Question: Who is the mens doubles when womens doubles is anastasia chervyakova romina gabdullina?
SQL: SELECT "mens_doubles" FROM "past_winners" WHERE "womens_doubles"='Anastasia Chervyakova Romina Gabdullina';

Question: Who is themens doubles when the mens singles is flemming delfs?
SQL: SELECT "mens_doubles" FROM "past_winners" WHERE "mens_singles"='Flemming Delfs';

Question: Who was the womens doubles when the mixed doubles is jacco arends selena piek?
SQL: SELECT "womens_doubles" FROM "past_winners" WHERE "mixed_doubles"='Jacco Arends Selena Piek';

Question: Who was the mens doubles when womens singles is mette sørensen?
SQL: SELECT "mens_doubles" FROM "past_winners" WHERE "womens_singles"='Mette Sørensen';