Database Management Systems and its function.

 Purpose of Database Management Systems

Organizations use large amounts of data. A database management system (DBMS) is a software tool that makes it possible to organize data in a database.

The standard acronym for database management system is DBMS, so you will often see this instead of the full name. The ultimate purpose of a database management system is to store and transform data into information to support making decisions.

A DBMS consists of the following three elements:

1. The physical database: the collection of files that contain the data
2. The database engine: the software that makes it possible to access and modify the contents of the database
3. The database scheme: the specification of the logical structure of the data stored in the database

While it sounds logical to have a DBMS in place, it is worth thinking for a moment about the alternative. What would the data in an organization look like without a DBMS? Consider yourself as the organization for a moment, and the data are all the files on your computer. How is your data organized? If you are like most typical computer users, you have a large number of files, organized in folders.

You may have word processor documents, presentation files, spreadsheets, photographs, etc. You find the information you need based on the folder structure you have created and the names you have given to your files. This is called a file system and is typical for individual computer users.

Now consider the challenges you are faced with. Have you ever lost a file? Have you had difficulty finding a file? Probably. Perhaps you are using multiple computers and your files are located in different physical locations. And, when was the list time you created a backup of all your files? You do back up, right?

You probably get the picture. A file system is relatively simple, but it only works if you keep yourself very organized and disciplined. Now consider an organization with 1,000 employees, each with their own computer. Can you see some of the challenges when using a file system? Do you really want critical financial data floating around the offices as simple files on individual computers?

Functions of a DBMS

So, what does a DBMS really do? It organizes your files to give you more control over your data.

A DBMS makes it possible for users to create, edit and update data in database files. Once created, the DBMS makes it possible to store and retrieve data from those database files.

More specifically, a DBMS provides the following functions:

• Concurrency: concurrent access (meaning 'at the same time') to the same database by multiple users
• Data redundancy occurs when duplicate copies of the same data are stored in different places. With our student, Jamie, the teacher has to repeatedly input the name in every table it needs to appear, including the 11 subject tables. This is data redundancy. With a DBMS, data is stored in a one structured database, and data is inputted once in only one place. As a result, the teacher needs to key in Jamie's name just one time. In all other areas where this child's name is referenced, it will be taken from that particular data repository. The control of data redundancy in DBMS also saves storage space.
  Going back to our student, Jamie, is it J-A-I-M-E? Or J-A-M-I-E? Imagine the teacher having to get the spelling right in each of the 13 tables this child's name needs to appear. The possibilities of spelling errors are very high, considering we have 299 other students to input. By controlling data redundancy, we can automatically see how data consistency is attained.
• Data consistency: It means that in all instances within the database where a piece of data occurs, the data values are identical. With data redundancy controlled by adding, editing, and deleting data in one place, the DBMS automatically updates each occurrence of that piece of data within the entire database.
• Security: security rules to determine access rights of users
• Backup and recovery: processes to back-up the data regularly and recover data if a problem occurs
• Integrity: database structure and rules improve the integrity of the data
• Data descriptions: a data dictionary provides a description of the data

Within an organization, the development of the database is typically controlled by database administrators (DBAs) and other specialists. This ensures the database structure is efficient and reliable.

Database administrators also control access and security aspects. For example, different people within an organization use databases in different ways. Some employees may simply want to view the data and perform basic analysis. Other employees are actively involved in adding data to the database or updating existing data. This means that the database administrator needs to set the user permissions. You don't want someone who only needs to view the database to accidentally delete parts of the database.

Pros and Cons of DBMS

There are a number of benefits to using a DBMS.

A DBMS provides automated methods to create, store and retrieve data. It may take some time to set up these methods, but once in place, a DBMS can make tedious manual tasks a thing of the past.

A DBMS reduces data redundancy and inconsistency. Have you ever had different versions of the same file on your computer hard drive? The same thing happens in organizations. A well-designed DBMS will eliminate redundancy.

A DBMS allows for concurrent access by multiple users, each with their own specific role. Some users only need to view the data, some contribute to adding new data, while others design and manage the database - all at the same time!

A DBMS increases security and reliability. Database administrators are responsible for creating backups of databases, controlling access and, in general, making sure it works the way it was intended. Having one or more specialists control these tasks is a lot more effective than having each computer user in an organization having to worry about the security of their data.

A DBMS improves data quality. It is easy to make mistakes when entering data. A DBMS makes it possible to set up rules for the database. For example, when entering the phone number of a customer, you should not be entering text characters. A rule can be set up such that you cannot enter text in the phone number field. Or, think of specifying the state where a customer resides. It is easier to select from a pre-defined list of states than to have to type in the name.

As with any information system, there are also some disadvantages to using a DBMS.

Implementing a DBMS can be expensive and time-consuming. Typically, it requires database specialists to implement and maintain a database. More importantly, for a database to be really useful, it needs to be integrated into the existing business processes. In many cases, implementing a DBMS actually means some of those processes need to be changed. This may require training of existing staff and hiring of new staff. And of course, there are costs associated with the hardware and software needed to run a DBMS.

Any database remains vulnerable to security issues. As databases get larger and more complex, so does the challenge of keeping all the data secure. How often have you read a story of a computer hacker getting access to thousands of credit card numbers?

Multi-User Databases

One of the advantages of using a database management system is that multiple users can use the same database at the same time.

Consider for a moment how this is different from using a regular document stored on your hard drive. If you open a word processing or spreadsheet document on your computer, you are the only user. If you want to share this document with a colleague, you could e-mail it to them so they can save it on their hard drive. However, this creates a copy, and now there are two versions of the same file. Both you and your colleague can work with the data, but what happens if you both start making changes? You can see how this is going to get confusing.

Using a DBMS, you can store a database in a central location, such as a computer server. A server is a computer system that provides a network service. One of these services is data storage.

Now, both you and your colleague can work with the same database. Depending on the configuration of the DBMS, you can actually both edit the database at the same time. This does require that the database has been set up for multiple users and that each user has been given the proper permissions.

Lesson Summary

A database management system is a software tool that makes it possible to organize data in a database. It is often referred to by its acronym, DBMS. The functions of a DBMS include concurrency, security, backup and recovery, integrity and data descriptions.

Database management systems provide a number of key benefits but can be costly and time-consuming to implement. One of the key benefits of a DBMS is that multiple users can work with the same database at the same time at different locations.