Oracle删除主键或外键

--删除表的主键:
alter table table_name drop primary key cascade;
--OR
alter table table_name drop constraint pk_name cascade;

--删除表的外键

alter table s_stu drop foreign key cascade;

--例子

create table t1(id number constraint  t1_pk primary key);
create table t2(id number constraint t2_fk references t1(id));
--那么删t2里的外键约束:
alter table t2 drop constraint t2_fk;