Change Primary Key

Question

I have a table in Oracle which has following schema:

City_ID  Name  State  Country  BuildTime  Time

When I declared the table my primary key

Answer 1

You will need to drop and re-create the primary key like this:

alter table my_table drop constraint my_pk;
alter table my_table add constraint my_pk primary key (city_id, buildtime, time);

However, if there are other tables with foreign keys that reference this primary key, then you will need to drop those first, do the above, and then re-create the foreign keys with the new column list.

An alternative syntax to drop the existing primary key (e.g. if you don't know the constraint name):

alter table my_table drop primary key;