It seems the null constraint is ignored in the DBFDriver.
I downloaded the DBF_JDBC40.jar and ran the following sql:
create table test (x varchar(10), y varchar(10) not null)
insert into test (x) values ('hello')
select * from test
Without any error.
Additionally, the driver does not report non-nullable columns, for example using squirrel-sql on the created files, the database metadata reports IS_NULLABLE=YES for each column.
Is this expected behaviour?
Yeah. Xbase format doesn't support not null constraint.