Relational and Object-Oriented Databases - Case Study Example

Current State Of Database Technology Database technology started from flat file storages and over the years evolved into electronic data storages in the form of records and tables to complete relational and object-oriented databases. Today, the databases are not just restricted to objects, but they have also gone to the level of media support in the form of multimedia databases which support multimedia content to be stored in the databases. Today, with the increasing data requirements and storage needs, the databases have gone a step further. The emergence of data warehouses or advanced databases support huge data storage needs and provide analytical capabilities to stored data. The data stored in such databases includes the past data and archives too along with the current one. Object oriented databases have now become very popular as they provide a greater degree of flexibility in data storage and also provide a resource efficient storage mechanism. The data storage in the object oriented databases is in the form of objects instead of storing as rows and columns. The integration and connectivity of individual systems provide support to connect stand alone machines. In the current environment, the databases are all linked at the backend. This provides for client-server database architecture which gives a whole new dimension to existing database structure. The databases today are based on client-server architecture and provide support for multimedia content. They are huge in size as storage costs are not of much concern today. Data warehouses act as archives and analytical tool for the historical data. Relational Database Relational Databases Relational database was a revolution in the field of databases. The idea of having a tabular structure composed of rows and columns was a ground breaking proposition to make storage and retrieval easier than ever before. Peter Rob in his book describes the relational database in terms of storage and representation. The relational database model allows the designer to focus on the logical representation of the data and its relationships than the physical storage details. The tables are all logical, having the similar physical storage mechanisms at the backend. The relational databases are based on a row-column structure, each column being an attribute and a row as record. Each record or row can have a number of attributes for a particular record. Each table is referred to as relation, and hence called relational database, having a unique attribute(s) which make up the primary key. Each table is linked to one or more tables through the primary key and foreign key architecture. By structure, the relational database does not have any cap on storage limit, but due to storage limitations, they may act as constraints to the system. The relational databases use the concept of indexing for making the search faster and easier. The indexes are not the keys, but are attributes used for faster searching. They are the attributes which are frequently used for searching. The structure of relational databases can be seen in the following Entity Relationship Diagram and Relational Schema showing the entities and their attributes along with the relationships among them. Relational Databases Vs Other Databases The relational database is different from other databases in that the storage mechanism of relational databases is based on tables. 1. The flat file uses different files to store data 2. Object-oriented uses objects as storage units 3. Hierarchical makes and traces data based on their hierarchies 4. Network is similar to hierarchical but the hierarchies are in both directions, that is many parents can have a common child 5. Hybrid or Object-Relational Databases are becoming popular too. They have a mixed structure with the features of both the relational and object-oriented databases Theory E F Codd was a researcher at IBM. He proposed the model for the modern relational Database Management System. He presented the twelve points that any ideal relational database should follow. They are: i. The Information Rule All data should be presented to the user in table form. ii. Guaranteed Access Rule All data should be accessible without ambiguity. This can be accomplished through a combination of the table name, primary key, and column name. iii. Systematic Treatment of Null Values A field should be allowed to remain empty. This involves the support of a null value, which is distinct from an empty string or a number with a value of zero. Of course, this can't apply to primary keys. In addition, most database implementations support the concept of a nun- null field constraint that prevents null values in a specific table column. iv. Dynamic On-Line Catalog Based on the Relational Model A relational database must provide access to its structure through the same tools that are used to access the data. This is usually accomplished by storing the structure definition within special system tables. v. Comprehensive Data Sublanguage Rule The database must support at least one clearly defined language that includes functionality for data definition, data manipulation, data integrity, and database transaction control. All commercial relational databases use forms of the standard SQL (Structured Query Language) as their supported comprehensive language. vi. View Updating Rule Data can be presented to the user in different logical combinations, called views. Each view should support the same full range of data manipulation that direct-access to a table has available. In practice, providing update and delete access to logical views is difficult and is not fully supported by any current database. vii. High-level Insert, Update, and Delete Data can be retrieved from a relational database in sets constructed of data from multiple rows and/or multiple tables. This rule states that insert, update, and delete operations should be supported for any retrievable set rather than just for a single row in a single table. viii. Physical Data Independence The user is isolated from the physical method of storing and retrieving information from the database. Changes can be made to the underlying architecture (hardware, disk storage methods) without affecting how the user accesses it. ix. Logical Data Independence How a user views data should not change when the logical structure (tables structure) of the database changes. This rule is particularly difficult to satisfy. Most databases rely on strong ties between the user view of the data and the actual structure of the underlying tables. x. Integrity Independence The database language (like SQL) should support constraints on user input that maintain database integrity. This rule is not fully implemented by most major vendors. At a minimum, all databases do preserve two constraints through SQL. No component of a primary key can have a null value. If a foreign key is defined in one table, any value in it must exist as a primary key in another table. xi. Distribution Independence A user should be totally unaware of whether or not the database is distributed (whether parts of the database exist in multiple locations). A variety of reasons make this rule difficult to implement; I will spend time addressing these reasons when we discuss distributed databases. xii. Nonsubversion Rule There should be no way to modify the database structure other than through the multiple row database language (like SQL). Most databases today support administrative tools that allow some direct manipulation of the datastructure. (Codd's 12 Rules DATA MANAGEMENT STRATEGIES) Most of the Database systems and packages available do not follow all the rules, but they are the proposition for any database package to be ideal. In relational database, the relations (tables) are the major units of storage. Relations are made up of Rows and Columns. Rows make up records and Columns form Attributes. Rows are also referred to as Tuple. Codd also worked on the structure of databases in terms of storage of data at the backend. Along with his partner Ted, he developed the mathematical model of the relational database management system. This was revolutionary in concept and provided a unique way to store data in the form of tables. E F Codd proposed relational algebra as the basis for database query language. The querying follows the algebra principles, even in SQL. Standards Various Database standards are in practice today. They include SQL (Structured Query Language), CORBA (Common Object Request Broker Architecture), and SOM (System Object Model) among others. SQL or Structured Query Language is one of the most commonly used languages for querying databases. Its variations are used by almost all the database systems available today. SQL is a powerful querying language with support for multi-table and multiple-join queries. SQL provides the support to query a number of tables in a completely customized manner. The user has the power to design queries with as many tables and joins as required. The constraints may be imposed by the DBMS implementing the SQL at the backend. Other standards are related to specific user needs and requirements. They include the CORBA, SOM and other standards. These are designed to provide a uniform and consistent usage and implementation of various features and functionality. CORBA provides the user and programmer with an easy to use transparent interface for interoperability of objects. These standards are now becoming industrial standards, SQL being in use by most of the database management systems. With the evolution of all the standards as industrial standards, the use and the functionality is becoming more standardized and simple in databases than in any other type of software. With the universal standards, the integration and communication between two different systems is now possible. Products Microsoft Access, available as part of Microsoft Office Suite, is a powerful and portable Relational Database Management System or RDBMS. The powerful of relational database, with an easy to use interface and the availability of wizards to help the user are all provided in this package. The major constraint that the users face in MS Access is the storage limit. Access restricts the size of its database to 2 GB in Office XP. The number of objects in any database is restricted to 32,768 and number of characters in any field can be up to 64. Beyond 50,000 records, the efficiency of Access Databases starts to decline. This becomes a major bottleneck for huge data storage needs. For normal use, Access suffices user requirements and needs but for huge data repositories, Access falls short. On the other hand, SQL server databases and the support of SQL Server Engine give it a whole new bunch of features and power. The SQL server databases are capable of storing Gigabytes of data with a high speed of processing and retrieval. SQL server can be used with any other language acting as the front end (the user interface). This makes it more flexible, making the database migration relatively easy. The major issue with the SQL databases is the requirement of SQL server to use the databases. The SQL server is not a viable option for those with small database requirements. The power users may opt for SQL databases and/or companies with multiple databases can dedicate an SQL server to hold all the databases. Fox Pro was taken over by Microsoft and since then, the enhancements in their Database and other areas were seen. Fox Pro later became Visual Fox Pro with the enhanced graphical interface and easy to use drag and drop controls and features for programmers to work with. Visual Fox Pro now provides a very good interface and interconnectivity with the .NET Framework which is becoming a very popular development platform. The integration features make Visual Fox Pro a very popular Database Development and Programming medium for developers. Latest developments and advancements in the SQL server package of Microsoft have made it a secure and fool proof data storage solution. The users can now enjoy the power of SQL in a very secure and a user-friendly interface gives it an unmatched advantage over its competitors. The SQL server is built on the basic SQL, Structured Query Language. The SQL server database systems are powerful as they are supported by the other Microsoft products too. The major advantage of SQL server is the integration provision with the Microsoft Visual Studio .NET Development platform which is widely used by the developer’s community. This makes it a preferred choice by the developers who are using the .NET framework for development. The other advantages of SQL server is the use of various types of front-ends with the SQL databases at the backend. This gives it immense power to provide a high quality interface in medium of choice with the power and capabilities of the SQL server at the backend. List of References 1. Codd's 12 Rules DATA MANAGEMENT STRATEGIES (Put May 07, 2001 in Newsletter, http://www.itworld.com in http://www.itworld.com/nl/db_mgr/05072001/) 2. Rob, P & Coronel, C 2002, Database Systems. 3. Microsoft Corporation Website, www.microsoft.com 4. 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