Формат
<column definition> ::=
<column name> <data type>
[<default clause>]
[<column constraint>...]
<column constraint> ::=
NOT NULL [<unique specification>]
| <references specification>
| CHECK (<search condition>)
<column definition> ::=
<column name> <data type>
[<default clause>]
[<column constraint>...]
<column constraint> ::=
NOT NULL [<unique specification>]
| <references specification>
| CHECK (<search condition>)