Database Coursework on a Rental System: Design

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Breakdown of Tasks

Gantt Chart For Design

Consideration of possible solutions

     As outlined in the Analysis stage, there are many problems with the current manual system in use for recording, storing and manipulating data. A computerised solution would be the most effective way to tackle these problems inherent in the current system. Obviously, there many types of computerised solution that one can use and different types of software that can be used to design and use the package on. However, firstly I shall discuss the ways one can go about obtaining such a package. These ways include:

  • Purchasing an off-the-shelf package at a reputable computer retailer
  • Getting a bespoke package developed specifically to the organisation’s needs using a team of in-house developers
  • Getting a bespoke package specifically developed to the organisation’s needs using a team of external developers
  • The customisation of an generic package

     Due to the various constraints of the project, namely time and money limitations, and the nature of it being an A level project, using a team of in-house or external developers to develop the package is simply out of the question. It is also not worth it if the task is merely not sufficiently complex to justify a having a specific piece of software developed for the purpose. If the problems can be addressed by merely using an off-the-shelf package, then having a tailor-made package designed is just unnecessary expenditure on the part of the organisation. I believe the problems with Fred’s Car Rentals’ system can be addressed via other means, and that’s even before one considers the exacerbation of this potential avenue of software acquirement by time and money constraints, so needless to say, Fred’s Car Rentals will not be using bespoke software.

     Another possible option is to buy an off-the-shelf package. It is relatively cheap compared to the cost of bespoke software, comes extensively tested and there is much support readily available. However, the features are not tailored to the organisation and may prove to be rather limited when it comes to the extent of the features that can be used.

     I believe the best option available for this project is to customise a generic package, which represents a compromise between the money-friendly, extensively tested off-the-shelf-software and the tailor-made nature of bespoke software. The customisation of a generic software package involves choosing a suitable package for the project and altering it to make it suitable for the tasks the user will have to perform, containing all the features that they will need.

     There are a number of generic packages that can be chosen for this project. These include:

Spreadsheet Packages: these types of packages can hold, store and manipulate numerical data but not at a particularly advanced level. They consist of a series of columns and rows of “cells”, which are boxes that can hold data. A cell may contain formulae for calculating values based upon other values in the system using these said values in a mathematical relationship in order to produce a required value defined by the user. Other features include the locking of cells to ensure that they are not accidentally overwritten and the defining of data types to cells or cell groupings that includes date, currency and percentage data types.

     The limitations of this type of generic package include a lack of security, concurrency and data redundancy and inconsistency. Generally, if a person has permission to access a spreadsheet, they also have permission to modify its contents, making it easy for someone to commit fraud. Also, the lack of concurrency means that only one user is allowed to be making changes at any given time. All the data is stored in one file, so it can hold a flat file database. In this type of database the same data is often has to be repeated, leading to data redundancy and inconsistency.

Word Processing Packages: are used to create, edit, manipulate and print hard copies of textual documents. The common features of a word processing package include:

  • The ability insert text into the document
  • The ability to delete text from the document
  • The ability to remove a piece of text from the document (cut) and re-insert it somewhere else (paste)
  • A copy function which enables the duplication of a piece of text.
  • Search functionality that enables the user to search for a particular word or phrase in the text.
  • Font and text size specifications, as well as the ability to embolden, underline, or italicise sections of text.
  • The ability to insert graphical images into the document
  • Headers footers and page numbers
  • Macros
  • Mail merging
  • Spell-checker
  • Built-in dictionary and thesaurus

     Using the mail merge function, one can merge files from another file into another file of a mail-merge template. This way, if the same letter has to be sent to all of Fred’s Car Rentals’ customers, a new letter need not be typed up for each one. Their details need only to be inserted into the letter template. This type of package can also be used for advertisement materials such as business cards. Whilst I am using this type of software to type this project up, and will be using it to design a mail merge letter for the business, it is not a suitable package for the storage and manipulation of large volumes of data. Theoretically, all data could be held in tables created in a word-processing package. This approach would be severely lacking, with data redundancy, data inconsistency and limited ways in which data can be manipulated plaguing the system. Data cannot be queried.

Desktop Publishing Software (such as Microsoft Publisher): These packages can be used to create promotional material for an organisation, such as posters. They enable the insertion and manipulation of graphical images. However, beyond that they are rather limited in what they can do. Theoretically, one could design a graphical image containing data relevant to Fred’s Car Rentals. It would be pointless though, as the data containing within an image cannot be altered readily, or manipulated to the required degree. Therefore I will not be using this type of package to produce a solution for Fred’s Car Rentals.

Web-Authoring Package: These can be used to create a website for the company

that can be used for customer service and advertisement. The online presence of an organisation on the web increases the visibility of the organisation to potential customers, serving as a useful advertisement tool. However, in the context of storing and manipulating large volumes of data, web pages leave a lot to be desired. Theoretically, one can store and record data on a website, although the extent to which data can be manipulated is rather limited.

Presentation packages: these packages can be used to create a series of slides to present to an audience. This can be an internal presentation of ideas within the organisation itself or a public presentation. Whilst it serves this purpose well, I am not producing a solution for Fred’s Car Rentals for the purpose of presenting information. It does not make much sense to store and manipulate data using a presentation package, as the package does not have the necessary features to accommodate large volumes of data and manipulate and query this data to the extent required by the proposed solution.

Relational Database Management System packages: This type of package contains tools for the efficient storage and manipulation of data, creating and running complex queries on the data held and the subsequent production of reports from these queries, creating onscreen forms and menus for data input and system navigation respectively and the creation and subsequent attachment of macros. Data is held in multiple interrelated files so data redundancy is kept to a minimum and thus data consistency is maximised. This package seems like the best choice to use to develop the computerised solution for Fred’s Car Rentals.

     However, a spreadsheet package could also be used to a satisfactory degree for this project. The table below compares the attributes of both the spreadsheet and database packages, based on a number of criteria that the package should fulfil if an effective solution is to be created for this project.

     From viewing the above table, it is evident that a database package is superior to the spreadsheet package in creating the computerised solution for Fred’s Car Rentals. The package contains many more useful features that can be harnessed to address the problems inherent in the organisation’s current system. As a result, this will be the type of package I will use for this project. The database package I will use is Microsoft Access. The reason that I chose this particular package over other database software is because I have experience in using it and it is the only database package available to me on both the school computers and my home computer.

Features of Microsoft Access

     Microsoft Access is a relational database management system from the Microsoft Corporation, one of the applications in the Microsoft Office Suite of applications. It is a program that can be used to create and manage a collection of centralised, structured data for its subsequent manipulation. As outlined before, this piece of software is most suited to the task containing many useful features. Features of Access that I intend to use to design a computerised solution for this project are:

Entity Creation: - Access enables the creation of multiple entities in the system. This will permit the creation of customer, staff, vehicle, manufacturer, rental, and return entities that are required by the new system, along with each entities respective rentals.

Entity Relationship Modelling: - Relationships between entities will be created using Access’s relationship function. There are various degrees of entity relationships that can be designated; One-to-one, one-to-many and many-to-many. In one-to-one entity relationships, for every instance that one of the entities in the relationship occurs once, the other entity occurs once as well. For example, one teacher can have one classroom and this classroom can have the one teacher. In a one-to-many relationship, for every occurrence of entity A, there are many occurrences of entity B. For example, one manufacturer produces many vehicles, but each vehicle has one manufacturer. In a many-to-many relationship, many occurrences of an entity in the relationship are linked with many occurrences of the other entity in the relationship. For example, an order can be made for more than one product and a product can be included in more than one order.

Input masks: - These are string expressions defined by the user, which acts as a template to govern the data entered into the system. This way, data integrity is improved by reducing the chance of transcriptions errors on the part of the data entry clerk. For example, a postcode field can have an input mask of “LL00 0LL”, dictating that the data entered must consist of two letters followed by three digits and ending in two letters. This reduces the amount of possible mistakes that can be made, and if an error is made, the user will detect this as a letter cannot be entered when the input mask requires a digit, and vice versa.

Validation Rules: - Validation rules are techniques used in the process of data validation. These rules check that data falls within the parameters defined by the systems analyst. Examples of such rules include size checks, in which the item of data entered is checked for character length to ensure it is of the required length. For instance, an ISBN number should be exactly 10 characters long. Another example is a range check, in which entered data must fall between two user-defined parameters.

Data Input Forms: - Microsoft Access facilitates the creation and display of onscreen data input forms for new records to be entered into the system, created from the entities held in the database. These data input forms can be customised with the addition of buttons, which upon being clicked on by the user perform a pre-defined command, which can be a functions such as “Add record”, “Delete Record”, “Save Record” or “Close Form”. Images can be inserted into these forms along with colour to make them more aesthetically pleasing to the user. This has a psychological effect on a user interacting with the system on a regular basis, as they are more likely to become de-motivated and bored if the interface is colourless and without images. Extra functionality can be added to these forms via the inclusion of appropriate sub-forms, displaying related information from other entities.

Formulae: - Formulae can be incorporated into the system for the calculation of values based upon other attributes in a record. For example, a customer’s age can be calculated by subtracting their date of birth from today’s date. This reduces the amount of mental arithmetic that has to be performed by employees, thus increasing the accuracy of data held within the system.

Combo Boxes: - The ability to create combo boxes in Microsoft Access is best used there are a small, limited number of values that can be entered into a certain field. For example, in a field such as “title” that is to precede a customers name, the values that can go in this field are typically limited to Mr, Mrs, Miss and Dr. It makes no sense to allow users to manually type one of these values into the system each time there is a new customer. Instead, a combo box is created. When clicked, the combo box will display a drop-down list of these values to select from. It saves time and decreases likelihood of human error.

Drop-Down Lists: - drop-down lists can be included in tables when there are a small, limited number of values that can be added into that field. . For example, in a field such as “sex”, the values that can go in this field are typically limited to male and female. They basically are to tables what combo boxes are to forms.

Macros: - A macro is a pattern that determines how particular sequences of input should be mapped to an output sequence. This includes autoexec macros that run a sequence of pre-specified instructions as soon as the database is opened, macros that display information in a display box when the user clicks a button and macros that perform actions such as opening different forms, tables and reports when clicked.

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Queries: - Queries can be used in Access to extract useful information from the database. There are various types of queries that can be used. Select queries extract data from tables based on specified values, find duplicate queries display records with duplicate values for one or more of the specified fields, and find unmatched queries display records from one table that do not have corresponding values in a second table.

Reports: - Reports are a useful way of presenting useful information extracted by queries. They provide a way of organising the results produced by a query and sending it to ...

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