Other advantages that organizing information in a database brings are integrity of data and greater security of data. With a database management system (DBMS), users are provided with the ability to specify constraints on data such as making a field entry essential or using a validation routine. A DBMS can also ensure that only authorised users are allowed access to the data. This also means that you can have a centralised control of data, the database administrator will control who has access to what and will structure the database with the needs of the whole department in mind.
In addition to all of this, the database approach will make more information available to the users as they have access to a wider range of data that was previously held in separate departments and sometimes on incompatible systems. It can also increase productivity as a DBMS provides an easy to use query language that allows users to get immediate response from their queries rather than having to use a specialist “programmer” to write queries for them.
INFORMATION SYSTEMS DEVELOPMENT
ASSIGNMENT 2003-04
2. What are the primary features of a database management system?
A database management system (DBMS) is a set of programs which typically manage large structured sets of persistent data, offering specific query facilities to many users. They are used widely in business applications. A DBMS can be thought of as a file manager that manages data in databases rather than files in file systems.
The DBMS can be a highly complex set of software programs that administer the organisation, storage and retrieval of data (fields, records and files) in a database. It manages user requests (and requests from other programs) so that users and other programs are free from having to understand where the data is physically located on storage media and, in a multi-user system, who else may also be accessing the data. The DBMS accepts requests for data from the application program and instructs the operating system to transfer the appropriate data.
In handling user requests, the DBMS ensure the integrity of the data, making sure it continues to be accessible and is consistently organized as intended. It upholds the integrity of the database by not permitting more than one user to update the same record at the same time and by keeping duplicate records out of the database. It also ensures security, making sure only those with access privileges can access the data. With the use of passwords, users are allowed access to the entire database or subsets of the database.
When a DBMS is used, information systems can be altered much more easily as the organisation’s information requirements change. New categories of data can be added to the database without disruption to the existing system.
INFORMATION SYSTEMS DEVELOPMENT
ASSIGNMENT 2003-04
3. What is a data warehouse?
A data warehouse is a separate database dedicated to decision support. It is frequently very large and can access all of a company's information. Data is transferred from transaction processing systems and integrated. It is accessed to provide management information through report writers, query tools, data access and retrieval tools, OLAP servers and enterprise information systems. It is software architecture, not a product.
While the warehouse can be distributed over several computers and may contain several databases and information from numerous sources in a variety of formats, it should be accessible through a server. Thus, access to the warehouse is transparent to the user, who can use simple commands to retrieve and analyze all the information. The data warehouse also contains data about how the warehouse is organized, where the information can be found, and any connections between data. Frequently used for decision support within an organization, the data warehouse also allows the organization to organize its data, coordinate updates, and see relationships between information gathered from different parts of the organization.
It brings together data from multiple transactional systems and enables users to access and analyze the information at various levels throughout an enterprise.
According to William Inmon, who is widely considered as the father of the modern data warehouse, a data warehouse is a “subject-oriented, integrated, time-variant, non-volatile collection of data in support of decision making” (1990, quoted by Highlander).
INFORMATION SYSTEMS DEVELOPMENT
ASSIGNMENT 2003-04
BIBLIOGRAPHY
Zwass, Management Information Systems, Brown, 2002