删除表中已有的主键约束
(1)有命名
alter table students drop constraint yy;
(2)无命名
可用 SELECT * from user_cons_columns;
查找表中主键名称得student表中的主键名为SYS_C002715
alter table student drop constraint SYS_C002715;
or
alter table ptrs_config drop primary key
3、向表中添加主键约束
alter table student add constraint pk_student primary key(studentid);
标签:删除,constraint,alter,student,表中,table,主键 From: https://blog.51cto.com/u_16174476/6604304