column-definition 1 column-name 2? FOR 2.1! COLUMN 2.2 system-column-name 3 data-type (1) 4+ 4? 4 default-clause 4.0! GENERATED ALWAYS 4.0? 4.0 GENERATED BY DEFAULT 4.1 (2) 4.1? 4.1 identity-options 4.1 as-row-change-timestamp-clause 4 NOT NULL 4! NOT HIDDEN 4? 4 IMPLICITLY HIDDEN 4 column-constraint 4 FIELDPROC external-program-name 4.1? 4.1 ( 4.1.1+ , 4.1.1 constant 4.1.2 ) 4 datalink-options (3) 5 (4) data-type 1 built-in-type 1 distinct-type-name