DuckCorp Dico

Found one definition

1.                 From The Free On-line Dictionary of Computing (19 January 2023):
                   
   
   
                   
                     
   null
      <programming> A special value used in several languages to
      represent the thing referred to by an uninitialised pointer.
      <database> A special value that may be stored in some database
      columns to represent an unknown, missing, not applicable, or
      undefined value.  Nulls are treated completely differently
      from ordinary values when evaluating SQL expressions and there
      are several SQL constructs for dealing with nulls.
      (2003-06-17)