Documentation implies column NOT NULL constraint cannot be named, but it can be.

Cf syntax description in ref/rrefsqlj16095.html:

Column-level-constraint

{
NOT NULL |
[ [CONSTRAINT constraint-Name]
{
CHECK (searchCondition) |

{ PRIMARY KEY | UNIQUE | REFERENCES clause }

}
}

but actually this works:

create table t(i int constraint foo not null); The curly braces around primary, unique and references are redundant as well.