Business level advantages of databases

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The main business benefits of databases derive from the way that databases are designed for
sharing information. They are superior for:

•  multi-user access – allowing different people in the business access to the same data simultaneously, such as a manager and another member of staff accessing a single customer’s data
• distributed access – users in different departments of the business can readily access data
•  speed – for accessing large volumes of information, such as the customers of a bank, only databases are designed to produce reports or access the information rapidly about a single customer
•  data quality – sophisticated validation checks can be performed when data are entered to ensure their integrity;
• security – access to different types of data can readily be limited to different members of staff. In a car dealership database, for example, the manager of a single branch could be restricted to sales data for their branch;
• space efficiency – by splitting up a database into different tables when it is de-signed, less space is needed, as will be seen in the section on normalisation

Despite the many advantages of databases, there are certain information management applications where other software, such as spreadsheets, are more appropriate. For instance, in some cases it is:

•  easier and faster to create a spreadsheet structure;
• easier and faster to enter data using facilities such as auto-filling the months;

An overview of the types of database
Approaches to the design of electronic databases include file processing databases, database management systems, relational database management systems, object-oriented databases and network and hierarchical databases. The following provides a brief overview of each of these approaches.

File processing databases
Early data processing systems were based around numerous files containing large amounts of data related to daily business transactions. As a result, many organisations found themselves in a position where they held large amounts of valuable data but were unable to maximise their use of them. A major problem stemmed from the fact that the data held were often stored in different formats, for example completely different structures might be used to store details of sales and purchases. In order to make use of these data, it was usually necessary to create specialised computer programs, often at great expense. This type of database is sometimes described as having a flat file structure. A flat-file database can be described as being self-contained since it contains only one type of record – or table – and cannot access data held in other database files. A free-form database allows users to store information in the form of brief notes or passages of text. Each item held can be placed within a category or assigned one or more key words. Information is organised and retrieved by using categories or key words.

A modern variation on free-form databases is the hypertext database. In a hypertext database information is stored as series of objects and can consist of text, graphics, numerical data and multimedia data. Any object can be linked to any other, allowing users to store disparate information in an organised manner. A good example of a free-form database is the help files found within most software packages. An example of a hypertext database is the pages available via any given site on the World Wide Web.

Database management systems
The introduction of database management systems altered the way in which organisations managed their data resources. Although data were still held separately from the programs that made use of them, this new approach offered greater flexibility whilst reducing development and operating costs. Some of the major characteristics of the database management system (DBMS) approach included:

Programs included a range of general-purpose tools and utilities for producing reports or extracting data. This meant that comparatively little development was needed in order to undertake new tasks.

• The availability of general-purpose tools enabled non-technical users to access data. Users were able to analyse data, extract records and produce reports with little support from technical staff.
• The use of a DBMS encouraged organisations to introduce standards for developing and operating their databases. As an example, many organisations developed standards governing the structure of any new data files created.

Relational database management systems
The popularity of the relational database management system (RDBMS) approach grew from a need to share data resources across the entire organisation. In the past, it had been normal to concentrate resources in a small number of specific areas. For example, an organisation’s accounting and stock control functions often dealt with the largest number of business transactions and were seen as having the greatest need of the organisation’s information technology resources. In the same way, these functions were also seen as having the greatest need of the organisation’s data resources. However, as companies aimed to become more efficient and reduce costs it became essential to ensure the widest possible access to organisational data resources. In addition, organisations were also beginning to receive increased demands for information from users and managers.

The RDBMS approach can be seen as an extension of the DBMS approach with the additional benefits to be gained by sharing data across an organisation and the ability to combine data from several different sources. As an example, it is possible to reduce stockholding costs by linking together an organisation’s production and stock control functions. Such an approach would allow stock levels to be adjusted continuously by examining production levels. In this way, stocks of raw materials can be increased or decreased according to actual usage. In the same way, production scheduling might be improved by inspecting stock levels at regular intervals.

Figure 4.1 illustrates how records can be linked together using record keys. The diagram illustrates a simple relational database containing two tables: one holding details of an employee’s pay, the other holding personal information, such as the employee’s address. The database is to be used to generate pay slips for all employees. In order to accomplish this, theDBMS would carry out the following actions for each record in the Personal Details table:

1. Locate a record within the Personal Details table. The unique primary key can be used to identify a specific employee.
2. Extract any information required from the Personal Details record, such as the employee’s name and address.
3. The secondary key identifies a unique record in the Pay Details table. Since the secondary key in the Personal Details table matches the primary key in the Pay Details table, the DBMS can locate the specific record required.
4. The information required from the Pay Details table is extracted and the pay slip is printed.

Object-oriented databases
An object-oriented approach to database design employs the concept of reusable objects in order to develop sophisticated or complex applications. An object combines data structures with any functions needed to manipulate the object or the data it holds. As an example, an

object called Employee might be created to store details of staff. The object would contain a data structure that allowed basic details such as name, address, age, etc. to be stored. In addition, the object would also contain facilities that allow various actions to be performed, such as changing an employee’s address.
This object-oriented approach offers several important advantages:

•  Since objects are self-contained, they are easy to manage, for example changes can be made to an individual object without necessarily altering any other part of the system.
•  New objects can be created quickly and easily from existing ones. Continuing with the example given previously, the Employee object might be used as the basis for a new object entitled Manager. Only minor changes would be needed to complete the new  object since it would already share most of the features of Employee. 
• Objects can be copied or transferred into new systems with little difficulty. Since the object already contains any functions needed to make use of it, it can be used immediately within the new system.

Network and hierarchical databases
Mention of these types of databases is included for completeness. These are alternatives to the relational model and were its competitors in the 1980s. In the 1990s, the vast majority of business applications became RDBMS-based, but with object-oriented techniques being used increasingly. The network or hierarchical model may be used for some highperformance applications such as data warehouses (although many of these are based on RDBMS).

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