CREATE TABLE table_name_68 (date VARCHAR2, result VARCHAR2, location VARCHAR2, year VARCHAR2, loser VARCHAR2)

Which date had a year under 1988, loser of Philadelphia Eagles, location of Giants Stadium, and a result of 21-0?
SELECT date FROM table_name_68 WHERE year < 1988 AND loser = "philadelphia eagles" AND location = "giants stadium" AND result = "21-0"
SELECT "date" FROM "table_name_68" WHERE "21-0" = "result" AND "giants stadium" = "location" AND "loser" = "philadelphia eagles" AND "year" < 1988