isql 192.168.0.201/3330:empty30 -user sysdba -pas masterke
Database: 192.168.0.201/3330:empty30, User: sysdba
SQL> create table autoid_test(id int generated by default as identity primary key, f01 int);
SQL> insert into autoid_test(f01) values(100);
SQL> insert into autoid_test(f01) values(200);
SQL> insert into autoid_test(f01) values(300);
SQL> commit;
SQL> select * from autoid_test; commit;

          ID F01
============ ============
           1 100
           2 200
           3 300

SQL> show sequ;
There are no generators in this database
SQL> commit;

-- now we create non_priviledged user and give him all possible rights for DML operations:
SQL> create user u30tmp1 password '123'; commit;
SQL> grant insert,update,delete,select on autoid_test to u30tmp1; commit;

-- connect under just created user and check what he really can do with that table:
SQL> connect '192.168.0.201/3330:empty30' user 'u30tmp1' password '123';
Database: '192.168.0.201/3330:empty30', User: u30tmp1
SQL> select * from autoid_test; -- OK

          ID F01
============ ============
           1 100
           2 200
           3 300

SQL> update autoid_test set f01=-f01 where id=1; -- OK
SQL> delete from autoid_test where id>1; -- OK
SQL> insert into autoid_test(f01) values(555); -- error
Statement failed, SQLSTATE = 28000
no permission for USAGE access to GENERATOR RDB$1