CREATE TABLE table_35270 ("Outcome" CLOB, "Date" CLOB, "Tournament" CLOB, "Surface" CLOB, "Partner" CLOB, "Opponents in the final" CLOB, "Score" CLOB)

What date was the score of 6 3 6 4?
SELECT "Date" FROM table_35270 WHERE "Score" = '6–3 6–4'
SELECT "Date" FROM "table_35270" WHERE "Score" = '6–3 6–4'