Slide 12.8: Object tables vs relational tables with objects

Object Tables vs Relational Tables with Objects

Object Tables

Store row objects.
Are created by CREATE TABLE OF command.
Object identifier is generated for each row object by the system.

 SQL> CREATE TABLE  persons  OF  person_typ; 

 Table created.

 SQL> DESC  persons; 

          Name             Null?          Type
 ------------------------ -------- -------------------
 NAME                              VARCHAR2(32)
 SSN                               NUMBER(38)
 DOB                               DATE

 SQL> INSERT INTO  persons  VALUES (  
   2    'Powerpuff Girls', 123456789, '31-Oct-80' ); 

 1 row created.

 SQL> SELECT * FROM  persons; 

               NAME                  SSN        DOB
 -------------------------------- --------- ---------
 Powerpuff Girls                  123456789 31-OCT-80

Relational Tables with Objects
Column objects do not have the system-generated identifier, and therefore are not referenceable.

 SQL> CREATE TABLE  person_rel ( p   person_typ ); 

 Table created.

 SQL> DESC  person_rel; 

             Name               Null?       Type
 ---------------------------- -------- ---------------
 P                                     PERSON_TYP 

 SQL> INSERT INTO  person_rel  VALUES (  
   2    person_typ('Powerpuff Girls', 123456789, '31-Oct-80' ) ); 

 1 row created.

 SQL> SELECT * FROM  person_rel; 

                 P(NAME, SSN, DOB) 
 ------------------------------------------------------ 
 PERSON_TYP('Powerpuff Girls', 123456789, '31-OCT-80')