sql - PSQL - how to insert data to the altered table? -

i have employee table foreign key dno refers dnumber in department table. in department table there foreign key mgr_ssn refers ssn in employee table.

i created table using

alter table employee  add foreign key (dno) references department(dnumber)      on delete restrict on update cascade; 

(both dno , mgr_ssn not null)

but confused how insert data, because violates referential integrity constraint, suggestion?

thank :)

foreign keys not given "not null" constraint. if there new employee has not been assigned dept. or new dept no manager.

still, problem should use "deferrable" property of oracle constraints. means, constraint checked @ commit point only. can insert dno , empnos first, commit later. @ point there no constraint viokation fk exists.

alter table employee add foreign key (dno) references department(dnumber) deferred deferrable;

--do same dept

then, insert emp (...) insert dept(...) commit;