CREATE TABLE table_69193 ("Round" FLOAT, "Circuit" TEXT, "Date" TEXT, "Fastest lap" TEXT, "Winning driver" TEXT, "Winning team" TEXT, "Winning manufacturer" TEXT)

What was the date of Circuit Hockenheimring and the winning manufacturer being Mercedes-Benz?
SELECT "Date" FROM table_69193 WHERE "Circuit" = 'hockenheimring' AND "Winning manufacturer" = 'mercedes-benz'
SELECT "Date" FROM "table_69193" WHERE "Circuit" = 'hockenheimring' AND "Winning manufacturer" = 'mercedes-benz'