A basic predicate compares two values.

  basic-predicate =

  ----> value-expr --+-> = --+-> value-expr ---->
                     +-> <> -+
                     +-> ^= -+
                     +-> != -+
                     +-> < --+
                     +-> <= -+
                     +-> > --+
                     +-> >= -+

    See the Value_Expressions HELP topic for details on value
    expressions.