Purpose of using different types of PL/SQL collections in Oracle

Question

What is the main purpose of using collections in oracle ?

1. Index by tables

2. Nested tables

3. Variable size ARRAY

Answer 1

The main purpose of using collection is to improve application performance. By using collections, we can 'cache' static data that needs to be accessed frequently and need to be modified. This results in reduced calls to a database.

Also, if you need to process a number of items of a similar type, storing these items in a collection will allow you to loop through each element with ease, referencing each one by an index.

Refer this article for more detail information about collection