资料来源 : Free On-Line Dictionary of Computing

tuple calculus
     
         A form of {relational calculus} in which a
        variable's only permitted values are {tuples} of a given
        {relation}.
     
        {Codd}'s unimplemented language {ALPHA} and the subsequent
        {QUEL} are examples of the tuple calculus.
     
        (1998-10-05)