[HACKERS] Clarification of NULL values

from X3H2-97-030 (I think)


            c) Let P be any row of TS and let Q be any other row of TS,
              and let PVi and QVi be the values of Ki in these rows,
              respectively. The relative position of rows P and Q in the
              result is determined by comparing PVi and QVi according to
              the rules of Subclause 8.2, "<comparison predicate>", where
              the <comp op> is the applicable <comp op> for Ki, with the
              following special treatment of null values. Whether a sort
              key value that is null is considered greater or less than
              a non-null value is implementation-defined, but all sort
              key values that are null shall either be considered greater
              than all non-null values or be considered less than all non-
              null values. PVi is said to precede QVi if the value of the
              <comparison predicate> "PVi <comp op> QVi" is true for the
              applicable <comp op>.


And if anyone can follow that.......

Adrian

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