Adding foreign key constraints when modifying tables in Oracle foreign key constraints

a grammar

ADD CONSTRAINT constrint_name FOREIGN

KEY(column_name) REFEFRENCES

table_name(column_name) [ON DELETE CASCADE]

Two examples

1. SQL> create table userinfo_f4
2. 2(id varchar2(10) primary key,
3. 3 username varchar2(20),
4. 4 typeid_new varchar2(10));
6. 表已创建。
9. SQL> alter table userinfo_f4
10. 2 add constraint fk_typeid_alter foreign key(typeid_new) references typeinfo(typeid);
12. 表已更改。