PRESENTED BY: LASONYA SHELBY 04/18/2010 LSTE 7309 The Importance of Databases

Relational Database The term relational database was originally defined and coined by Edgar Codd at IBM Almaden Research Center in A relational database matches by using common characteristics found within the data set. The resulting groups of data are organized and are much easier for many people to understand.  Example: Real estate transactions in a town can be grouped by the year the transaction occurred; or it can be grouped by the sale price of the transaction; or it can be grouped by the buyer’s last name. Relational database theory uses a set of mathematical terms, which are roughly equivalent to SQL database terminology.

Relational Database contd. Relational databases, as implemented in relational database management systems, have become a predominant choice for the storage of information in new databases used for financial records, manufacturing and logistical information, and personnel data and much more. Relational Databases have been challenged by Object Databases, which were introduced in an attempt to address the object-relational impedance mismatch in relational database, and XML databases. The three leading commercial relational database vendors are Oracle, Microsoft, and IBM. The three leading source implementations are MySQL, PostgreSQL, and SQLite.

Database Normalization Normalization was first proposed by Codd as an integral part of the relational model. It encompasses a set of best practices designed to eliminate the duplication of data, which in turn prevents data manipulation anomalies and loss of data integrity. The most common form of normalization applied to databases are called the normal forms. Normalization is criticized because it increases complexity and processing overhead required to join multiple tables representing what are conceptually a single item.

Database Normalization contd. Database normalization is also the process in which a database structure is free from any uncertainties like update, insertion, and deletion incidences. In order to normalize a database it must be designed in the third normal form. In the third normal form, all data will be secured, and only certain areas of the table are subjected to any change. There are three major problems encountered in database normalization and they are: the update anomaly, the insertion anomaly, and the deletion anomaly.

Database Applications There are three types of applications and they are: Access, MySQL, and Oracle. Microsoft Office Access, previously known as Microsoft Access, is a relational database management system from Microsoft that combines the relational Microsoft Jet Database Engine with a graphical user interface and software development tools. Access stores data in its own format based on the Access Jet Database Engine. It can also import or link directly to data stored in other Access databases.

Database Applications contd. Microsoft Access is used to create simple database solutions. Access also includes a query interface, forms to display and enter data, and reports for printing. Microsoft offers a wide range of template databases within the program and for download from their website. These options are available upon starting Access and allow users to quickly use and enhance a database with pre-defined tables, queries, forms, reports, and macros. Microsoft Access also offers the ability for programming to create solutions using the programming language for Visual Basic for Applications (VBA), which is similar to Visual Basic 6.0 (VB6) and used throughout Microsoft Office Programs.

Database Applications contd. The Oracle Database (commonly referred to as Oracle RDBMS or simply as Oracle) is a relational database management system (RDBMS) produced and marketed by Oracle Corporation. As of 2009, Oracle remains a major presence in database computing. Larry Ellison and his friends and former co-workers Bob Miner and Ed Oates started the consultancy Software Development Laboratories (SDL) in SDL developed the original version of the Oracle software. The Oracle RDBMS stores data logically in the form of tablespaces and physically in the form of data files.

Database Applications contd. Oracle databases control simultaneous access to data resources with locks (alternatively documented as “enqueues”. The databases also utilize “latches”- low-level serialization mechanisms to protect shared data structures in the System Global Area. Oracle database software comes in 63 language-versions including regional variations such as American English and British English. Variations between versions cover the names of days and months, abbreviations, time-symbols such as A.M. and A.D., and sorting. Oracle Corporation provides database developers with tools and mechanisms for producing internationalized database applications: referred to internally as “Globalization”.

Database Applications contd. MySQL is a relational database management system which is an open source database. MySQL has unique storage engine architecture whose performance is very high. It supports large number embedded applications which makes it very flexible. MySQL has stored procedures and views which allows the developer to give a higher productivity, and allows transactions to be rolled back, commit and crash recovery.

Database Applications contd. MySQL can be used for both Windows and Linux. Managing database includes adding, accessing, and processing data in a database. Some of the advantages of MySQL are it is very highly efficient, open source, highly secured since all password traffic is encrypted connecting to a server, and it offers a high scalability in terms of size and connectivity. There are some disadvantages to MySQL which are: it does not support a very large database size as efficiently, it does not support ROLE, COMMIT, and Stored procedures in versions less than 5.0, and transactions are not handled very efficiently.

Database Applications contd. Many storage types are present in MySQL and they are: MyISAM, memory storage, example storage, CSV storage, the BLACKHOLE storage, and the NDCLUSTER. MySQL is designed for a specific purpose which is to query data contained in a relational database. MySQL is a set-based, declarative query language, not an imperative language such as C or BASIC. However, there are extensions to Standard SQL which add procedural programming language functionality, such as control-of-flow constructs.

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