Oracle Database 10g The Complete Reference

CHAPTER 34Collectors (Nested Tables and Varying Arrays)

Collectors make use of abstract datatypes. You should be familiar with the creation and implementation of abstract datatypes (see Chapter 33) before attempting to use varying arrays and nested tables.

Varying Arrays

A varying array allows you to store repeating attributes of a record in a single row. For example, suppose you want to track which of your tools were borrowed by which of your neighbors. You could model this in a relational database by creating a BORROWER table:

create table BORROWER(Name           VARCHAR2(25), Tool           VARCHAR2(25),constraint BORROWER_PK primary key (Name, Tool));

Even though the borrower’s Name value does not change, it is repeated in each record because ...