CREATE TABLE table_64723 ("Date" TEXT, "Tournament" TEXT, "Surface" TEXT, "Opponent" TEXT, "Score" TEXT)

What was the date of the tournament with a clay surface and an opponent of Irina Falconi?
SELECT "Date" FROM table_64723 WHERE "Surface" = 'clay' AND "Opponent" = 'irina falconi'
SELECT "Date" FROM "table_64723" WHERE "Opponent" = 'irina falconi' AND "Surface" = 'clay'