Is there a way to give names to already existing constraints?
for example :
create table employee (emp_id number(10),emp_name varchar2(20),
dept_id number(10),foreign key(dept_id) references department(dept_id));
In the above query I haven't named the foreign key constraint so after the creation of the table can I give a name to it also can the foreign key constraint be dropped without dropping the column??
Yes you can rename a constraint like this:
alter table t rename constraint old_name to new_name
Edit: I've forgotten about the second question. Yes you can drop a constraint without dropping the column. If you do not know the name of the constraint you can find it in user_constraints table like this:
select constraint_name
from user_constraints
where table_name = 'your_table'
and constraint_type ='R'
For the second part, yes you can drop the foreign key constraint.
