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Systems Analysis

Extracts from this document...

Introduction

Systems Analysis Systems analysis can be defined as a disciplined process, which begins with the establishment of user requirements for a given application and concludes with the implementation of fully operational system The main stages of systems analysis are often referred to as the system life cycle. The following sections give a brief overview of their functions within the systems analysis process. Feasibility study The aim of this stage is to establish whether or not a proposal for the computerisation of a particular application is worthwhile or feasible. In simple terms, the feasibility study has to answer questions such as: > "Will computerisation achieve the users' objectives?"; > "What type of system will be most suitable?"; > "Will it be financially worthwhile?" System investigation and design Assuming that the feasibility study produces a recommendation to proceed with computerisation of an application, then before any system specification is produced, an analysis has to be made of the processes and procedures involved in the application under consideration. For example, an analysis of Sales Order Processing should identify how orders are received, the order forms used and the procedures necessary to fulfil orders. Analysis is not simply the recording of an application as it currently operates through a variety of information gathering methods such as interviewing and observation, the requirements of a new system should be identified. Although the needs of the organisation are of obvious importance, employees are more likely to be concerned with matters of job satisfaction and working conditions. Successful implementation of a computerised system requires a great deal of work, involvement and willingness to co-operate by everyone concerned. If staff feel that their views have been considered such co-operation is more likely. Although users' views are Important an outside observer can often identify problems with current practice which have never been questioned. A systems analyst from outside the firm needs therefore, to possess qualities of tact and diplomacy if his or her views are to be considered. ...read more.

Middle

successful, partly because users can provide valuable insights into the practical aspects of system operation and partly because they will feel less motivated if they have had little or no influence on the final design. A formal organisation chart can be used to gain an overall picture of staff relationships and responsibilities but it should be borne in mind that designated and actual job responsibilities can differ radically. For example, it may turn out that a junior sales clerk is carrying out the checking of orders, which should be the responsibility of the sales supervisor. Thus, it may be necessary for the analyst to draw an alternative informal organisation chart to show the actual working relationships of staff. An example is given Apart from identifying working relationships between staff, it is useful to draw up brief job descriptions so that consultation on individual system procedures can take place with the appropriate staff. For example, a job description for a sales clerk may include the following activities: completion of standard order forms; checking stock availability; notification of orders to accounts. Therefore, although the sales departmental manager may have knowledge of such procedures, the sales clerk will have practical experience of their operation and should be consulted. System inputs A number of details concerning the data inputs to a system need to be established: * source. It may, for example, originate from a customer, a supplier, or another department in the business; * form. The data may arrive, for example, by telephone, letter, or a standard form such as an order form or supplier's invoice; * volume and frequency. For example, the number of orders received daily or weekly; * contents. For example. the individual items of data which appear on a supplier's invoice. Such information will allow the analyst to make recommendations on the most appropriate methods of computer input. The design of appropriate input methods also has to take account of several tasks involved with the collection and entry of data to a system: * recording. ...read more.

Conclusion

( 2NF applies to entities with composite keys, that is a primary key composed of two or more attibutes. An entity which is already in 1NF, with a single attribute primary key is automatically in at least 2NF) The STUDENT entity has a single attribute primary key and is therefore already in 2NF. The LOAN_BOOK entity has a composite primary key so we need to examine all the non-key attributes to ensure they are fully functionally dependent on the whole of the primary key. Non-key attribute Dependent on:- Title Book# ISBN Book# ReturnDate Book#, Stud# Therefore Title and ISBN need to be removed to form a new entity BOOK. Book# is included to provide a link. The tables in 2NF are now:- STUDENT(Stud#, Name, Address, TG, Tutor,) LOAN_BOOK(Book#,Stud#, ReturnDate) BOOK(Book#, Title, ISBN) 4. Third Normal Form - 3NF Rule - To be in 3NF an entity must be in 2 NF (and therefore in 1NF) and contain no non-key dependencies. Fields which are not part of the primary key must always depend on the primary key and not on anything else, such as another non key field. Consider the entity STUDENT, Name & Address depend on the primary key but Tutor depends on the Tutor Group code TG and not on Stud#. They should therefore be removed to form a new entity, TUTOR. A copy of the code TG is left in the student table to form a link. STUDENT(Stud#, Name, Address, TG) TUTOR(TG, Tutor) Consider the entity LOAN_BOOK, return date is dependent on the primary key and therefore already in 3NF. Consider the entity BOOK, title is dependent on the ISBN and not on the Book#, this should be removed to create a new entity ISBN. A copy of ISBN is left in the BOOK entity to provide a link. BOOK(Book#, ISBN) ISBN(ISBN, Title) The final tables are:- STUDENT(Stud#, Name, Address, TG) TUTOR(TG, Tutor) LOAN_BOOK(Book#,Stud#, ReturnDate) BOOK(Book#, ISBN) ISBN(ISBN, Title) H. T. Harvey 6-Feb-03 1 of 18 Chapter 18 ...read more.

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