CREATE TABLE table_name_40 (date VARCHAR, tournament VARCHAR, runner_s__up VARCHAR)

Which date was the Memorial Tournament held on, when Payne Stewart was runner-up?
SELECT date FROM table_name_40 WHERE tournament = "memorial tournament" AND runner_s__up = "payne stewart"
SELECT "date" FROM "table_name_40" WHERE "memorial tournament" = "tournament" AND "payne stewart" = "runner_s__up"