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Database Analysis & Design

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Introduction

Assignment 1 Introduction Within this report I will explain the following areas in detail, * Explain the different types of databases - flat file, hierarchical and relational. Compare the advantages and disadvantages of each. * Describe two analysis methodologies and again compare the advantages and disadvantages. This time use examples to illustrate your key points. * Describe the concepts involved in Logical Data Modelling. * Identify and describe potential modelling constraints that could arise from a logical data model using examples. * Finally discuss the benefits of Logical Data Modelling. Databases There are many different types of databases available for use; the three most common ones are, * Flat file database * Relational database * Hierarchical database I will now explain each database listing the advantages and disadvantages of each. Flat File Databases This section will show a description about flat file databases and the advantages and disadvantages Description A Flat File Database is a text file commonly only containing a record for each line in the file. This sort of database would be used for a simple phonebook sort database, showing peoples names with there telephone numbers and possibly addresses. This could also be used to keep track of friends. An example of a flat file database is a personal phonebook storing names and telephone numbers Advantages The advantages of a flat file database are, * It is a very simple database which is easy to use and understand, very little training will be needed to create and use one of these. * Easy to understand. * These are cheap to both create and to run as they are usually just simple text files. * Uses a small number of resources Disadvantages The disadvantages of a flat file database are, * Information is entered manually which may cause more errors in spelling and the way data is entered. * Data duplication, data can be entered more than once and there is no way of checking if the data has been used before ...read more.

Middle

* Review Design Prototype Check the correctness of the designed system. Again testing and reviewing are the main techniques used, since the test records and user's feedbacks are important to generate the user documentation. Within this stage deliverables are given towards the end, these are, a Design Prototype during the phase that end users get to test. At the end of the Design is stage the Tested System is handed over to the next phase. A user document is also a deliverable in this section. Disadvantages The disadvantages within this methodology are, * Difficult for employees to commit time to the process, this means the project may not be completed on schedule. * Consistency problems, this means the system will be unprofessional and not how the user wants it * Sometimes project cannot be split into sections, this means large tasks need to be completed, this is harder. * This methodology is not always reliant on good quality * Stages can often be rushed, this causes errors and poor quality products. SSADM Within this section I will describe what the SSADM methodology is and how it works, state the advantages and disadvantages and then give examples to support my key points. Description Structured Systems Analysis and Design Method (SSADM) is an approach to analysis and design of systems. This uses a Waterfall life cycle, within these information systems designs can be arrived at. 1. Analysis 2. Design 3. Implementation 4. Testing 5. Maintenance http://www.math.bas.bg/~nkirov/2006/NETB151/slides/ch13/images/waterfall.png The diagram above shows the stages involved in the waterfall life cycle. Feasibility A feasibility study is the work and research which is completed at the start of the project, this helps determine and document what will happen within the project and how it will work. Within this section the planning, organising and the management of resources will be analysed to help allow the project goals to be completed effectively and efficiently. ...read more.

Conclusion

Takes longer to plan The logical data model takes longer time to plan than just creating the system with simple planning. The whole model has to be taken in to consideration and each step must be carried out before moving on to the system. Hardware/Software The correct software is needed to create logical data models efficiently, is poor software is used then the end product will not be as good as it should. The final system must be taken into consideration, things such as, is it being created for one computer or a network of computers? The system would have to be more advanced and made available to different software and hardware to cover these different aspects, this then means spending more money and more time. Security The logical data model has different security issues, if someone gathers the details of the system then peoples details can be at risk and this is breaking the data protection act, this can result in the system being shut down. Other details about companies and about how things are created can be found and this will affect the system. Having user names and passwords on all the different files and on different levels, this will reduce the amount of security issues. This means only certain people can access certain information Budget The company must have sufficient budget to have the system created, this can be a time consuming and expensive process, the company must be able to encounter any problems and have spare money to overcome these. Final system If the final system is just completely relied on by the logical data model then the system may not be what is required and what the client wants, other planning needs to take place. ?? ?? ?? ?? National Diploma For IT Practitioners Unit: 11 - Data Analysis and Design Assignment: 1 Candidate Number: Centre Number: 47303 Name: Neil Gibson Page: 1 ...read more.

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