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Chapter 1: Introducing Oracle8iMost everyone has heard the cliche, "information is power." And is this ever true. When you think about it, one of the most important assets of any institution is its information. For example, a typical business must keep track of its customers, orders, product inventory, and employee information for obvious reasons. Additionally, the analysis of pertinent business information can help make a company more competitive. For example, a sales analyst can use current sales data to forecast future sales and identify trends that might help to improve overall business profitability.
In today's world of high technology, computers manage most information because they make it easy to organize, store, and protect valuable data. The proliferation of powerful personal computers and networks has made it possible for all businesses, large and small alike, to quickly and safely make information readily available to people that require access to it.
Computers typically store and organize large amounts of information within a database. A database, whether or not a computer manages it, is nothing more than an orderly collection of related information. A database safely stores information and organizes it for fast retrieval. For example, a business can use a database to store tables of customer records, corresponding sales orders, product parts, and employee lists. Various workers can then use the database to efficiently perform their jobs. For example, salespeople can quickly enter or look up sales orders, advertising executives can study and forecast product sales, and warehouse personnel can efficiently manage product inventories.
Types of Databases Databases come in many varieties. Inverted list, hierarchic, and network database models are older types of database systems that, in general, are inflexible and difficult to work with. These types of database systems were originally designed primarily for prescribed transactions that input data rather than dynamic environments where data analysis is critical.
The very weaknesses of these earlier systems are exactly why relational database systems now dominate newer information management systems. Relational databases are easy to understand, design, and build. Relational databases store and present all information in tables, an easily understood concept. Furthermore, relational databases hide the complexities of data access from the user, making application development relatively simple when compared to other types of database systems.
Object-oriented databases are a relatively new type of system that supports the object-oriented development paradigm. The primary goal of object-oriented thinking is to raise the level of abstraction so that it is more natural to design and build an information management system. For example, in an object-oriented database, complex data structures called objects closely model the entities in a business system, while methods match the business operations that act upon the objects in the system. So, rather than store tables of, say, customers, orders, and order line items, a database stores instances of customers and sales order objects. Associated methods stored in the database describe how to add, change, and delete customer and sales order objects.
Database Management Systems
A database management system (DBMS) is computer software that manages access to databases. A typical multiuser DBMS performs the following tasks, and more:
- A DBMS safely manages shared access to a single database among multiple concurrent users. For example, a DBMS locks data as users add and update information, so that users do not destructively interfere with one another's work.
- A DBMS uses computer resources wisely so that a large number of application users can perform work with fast response times for maximum productivity.
- A DBMS protects database information in such a way that it can reconstruct work lost due to anything from a simple power outage to catastrophic site disasters.
You can purchase any one of several commercially available DBMSs to build and manage databases. The market-leading DBMS in use today is Oracle Corporation's Oracle Data Server, also kno wn simply as Oracle. The latest version of Oracle is Oracle8i, and it is an object-relational database management system (ORDBMS). That is, Oracle8i is a database server that offers the capabilities of both relational and object-oriented database systems. The goal of this book is to teach you how Oracle8i works and how to get started using the software's most typically used features.
Oracle8i, Building on Oracle7 and Oracle8
Oracle8i builds on the strengths of its predecessors, Oracle7 and Oracle8.0. Oracle7, originally released in early 1993, set a lofty standard for high-end relational database management systems. Oracle7's many features made it a potent database server for all types of common business applications, including:
- Online transaction processing (OLTP)--applications that process many small update transactions, such as banking, reservation, and order-entry systems
- Decision support systems (DSS)--applications that query targeted information from a database for the purposes of data analysis
- Data warehousing-applications that access large, read-only databases that are specifically optimized for fast access to even the most esoteric bits of information
Oracle8.0, released in the summer of 1997, added many new features to extend the power of Oracle7 and make Oracle suitable for even the most demanding and complex application environments. New Oracle8.0 features included data partitioning, object types and methods, large object (LOB) datatypes, password management, the Recovery Manager utility, and more.
Oracle8i, released in the spring of 1999, is the most recent release of Oracle. Oracle8i enhances the original release of Oracle8 in two primary areas: data warehousing and Web-based application development. For data warehousing, Oracle8i includes many new features specifically designed to increase the performance of complex query processing, such as materialized views, automatic query rewrite, and function-based indexes. For Web-based application development, Oracle8i ships with a Java VM (virtual machine) so that developers can build all application components using Java (including Java-based stored procedures, functions, and packages), or access existing database information using Java applications. A future release of Oracle8i will also include Oracle's Internet File System (IFS), which is essentially a drag-and-drop interface for manipulating database information. Subsequent chapters in this book will teach you how to use several of Oracle8i's new features.
Oracle8i License Options
Oracle8i is available in several different license formats:
- Oracle8i The basic version of Oracle8i that includes the most commonly used options and features available with Oracle8i.
- Oracle8i Enterprise Edition The complete version of Oracle8i that provides multiuser access to all features, including features for high-end database processing, Web-based database access, and data warehousing...