CREATE TABLE "canadian_national_championships_and_cana" (
  "year" real,
  "men_s_singles" text,
  "women_s_singles" text,
  "men_s_doubles" text,
  "women_s_doubles" text,
  "mixed_doubles" text
);

Question: What year did dave f. mctaggart win the men's singles and robert b. williams ethel marshall win the mixed doubles?
SQL: SELECT MAX("year") FROM "canadian_national_championships_and_cana" WHERE "men_s_singles"='dave f. mctaggart' AND "mixed_doubles"='robert b. williams ethel marshall';

Question: Who won the women's singles before 1958 when dave f. mctaggart won the men's singles?
SQL: SELECT "women_s_singles" FROM "canadian_national_championships_and_cana" WHERE "men_s_singles"='dave f. mctaggart' AND "year"<1958;

Question: Who won the men's singles in 1958?
SQL: SELECT "men_s_singles" FROM "canadian_national_championships_and_cana" WHERE "year"=1958;

Question: Who won the mixed doubles in 1957 when judy devlin won the women's singles?
SQL: SELECT "mixed_doubles" FROM "canadian_national_championships_and_cana" WHERE "women_s_singles"='judy devlin' AND "year"=1957;