CREATE TABLE table_name_42 (attendance NUMBER, opponent VARCHAR2, record VARCHAR2)

What is the attendance of the game that has the opponent of The Nationals with a record of 68-51?
SELECT SUM(attendance) FROM table_name_42 WHERE opponent = "nationals" AND record = "68-51"
SELECT SUM("attendance") FROM "table_name_42" WHERE "68-51" = "record" AND "nationals" = "opponent"