col-constraint=

   ---+---------------------------------++
      +-> CONSTRAINT <constraint-name> -+|
    +------------------------------------+
    +-> PRIMARY KEY -----------------+
    +-> UNIQUE ----------------------+
    +-> NOT NULL --------------------+
    +-> NULL ------------------------+
    +-> CHECK (predicate) -----------+
    +-> references-clause -----------+
    +------------>-------------------+
    +-------------<------------------+
    +----+----------------------------+-->
         +--> constraint-attributes --+

    Specifies a predicate that column values inserted into the table
    must satisfy.