An Object Relational Database Management System

1371 Words Jun 7th, 2015 6 Pages
INTRODUCTION
An object-relational database management system (ORDMS) is a DBMS that supports both relational and object-oriented functions. SQL:1999 seems like the most innovative update to the language since its induction, largely because of the adoption of object-oriented related upgrades.
COLLECTION TYPES
“A collection is an ordered group of elements, all of the same type.” (Oracle 2002) With this addition it became possible to use set operators which allows for a single result from two queries.
Operator Returns
UNION All distinct rows selected by either query
UNION ALL All rows selected by either query, including all duplicates
INTERSECT All distinct rows selected by both queries
MINUS All distinct rows selected by the first query but not the second
Arrays in Oracle are also referred to as collections and refer to a set of ordered data items of which each item is the same type. Each item is referred to as an element and each element has an index. “Oracle provides three types of PL/SQL collections: associative arrays, nested tables, and varrays.” (PSOUG.org 2009)
1. Associative arrays (index-by tables) – These provide flexibility when it comes to its values as it can be have negative or string values with no fixed limit and without the obligation of being sequential. Because the array is constructed in memory often this method is best implemented in small or medium lookup tables.
2. Nested tables – this is a column that can hold a table that uses sequential numbers…
Open Document