《数据厍设计与开发》讲义 1.4.2.10 RacLe中对象类型 例 想着外码,理解REF create type c_t as object( ; create table c of e-t create type a t as object(.) primary key(cid)) create type p_t as object( ;create table a/of a_t create type o t as object (primary key(aid)) (ordno int, month chaF(2) create table p of p-t cid char(3),aid ehar(3) (primary key(pid)) pid char(3), qty int create table o of o t dollars double precision, (primary key(ordno oc ref c t scope for (oc)Is c, oa ref a scope for(oa)is a op ref p t) scope for(od)is p 家邮电大学物你学院 部明80080北京邮电大学软件学院 郭文明 2003.06 《数据库设计与开发》讲义 1.4.2.1 ORACLE中对象类型 create type c_t as object (…); create type a_t as object (…); create type p_t as object (…); create type o_t as object (ordno int,month char(2), cid char(3),aid char(3), pid char(3),qty int, dollars double precision, oc ref c_t, oa ref a_t, op ref p_t); create table c of c_t (primary key (cid)); create table a of a_t (primary key (aid)); create table p of p_t (primary key (pid)); create table o of o_t (primary key (ordno), scope for (oc) is c, scope for (oa) is a, scope for (od) is p); 想着外码,理解REF • 例: