and { only { filter_eq { all_rows ; game site ; wrigley field } } ; eq { hop { filter_eq { all_rows ; game site ; wrigley field } ; date } ; october 21 , 1962 } } = true
select the rows whose game site record fuzzily matches to wrigley field . there is only one such row in the table . the date record of this unqiue row is october 21 , 1962 .