I have been given the task to design a database for a company called Postquick Parcels. Postquick Parcels is a company, which provides a parcel delivery service, which allows customers to send consignment parcels around the UK.

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INTRODUCTION        

Methods of Gathering data        

Problems of Present System        

Objectives of the new system        

The Feasibility of a Computer Based System        

Hardware        

Choices of Software        

Data requirements        

The Data Flow        

Entity-Relationship diagrams        

Outputs        

Forms        

Menu        

Methods of Data Entry        

Record structure        

Customer Records        

Destination Records        

Parcel Records        

File Organisation        

Security and Integrity of Data        

Integrity        

Safety        

IMPLEMENTATION        

Starting with a simple Database        

The Tables        

Linking the Tables        

Entering Data        

Customer Data Form        

Parcel Data Form        

Destination Data Form        

Order Data Form        

Avoiding Human Errors using input masks        

Validation Rules        

Queries        

Simple Queries        

Parameter Queries        

Consignment note        

As a Query        

Buttons        

Making Menus        

Managers statistics        

Testing the Buttons        

Testing The Queries        

Finding existing destination        

Finding ID        

Finding price from weight and total dimensions        

Update Customer Information        


INTRODUCTION

I have been given the task to design a database for a company called Postquick Parcels. Postquick Parcels is a company, which provides a parcel delivery service, which allows customers to send consignment parcels around the UK.

THE SYSTEMS LIFE CYCLE

We have been told that we should only document the design, implementation and testing stages of our design. However if I were to document the complete production of the system I would have used the systems life cycle. The systems life cycle helps designers to approach the design of a system in a methodical way. There are several variations of the cycle but below is the most common.

  1. Problem Definition – the problem will be defined by the user

  1. Feasibility Study – investigate the system and decide if there is need for a new system

  1. Analysis – analyse the requirements and produce a specification

  1. Design – the design is produced

  1. Construction

  1. Testing – system is fully tested

  1. Implementation – system implemented and users trained

  1. Maintenance – there are three types of maintenance:
  1. Perfective maintenance, where you make the system easier to use or you add new facilities
  2. Adaptive maintenance, where you make changes to suit the changes in working environment
  3. Corrective maintenance, where you change something because of errors discovered in the original system

  1. Evaluation – evaluation of the system and if it meets the requirements of the user

METHODS OF GATHERING DATA

If I had had to collect my own user information on the requirements of the new system and what the problems were with the new system there are four techniques I could use these are: -

  1. Interviewing staff at different levels about the present system and what they would like to see from the new system.
  2. Sending out questionnaires and analyzing results.
  3. Observing current procedures with current system.
  4. Examine current business and systems documents and outputs.

PROBLEMS OF PRESENT SYSTEM

The Present Postquick Parcels postal delivery system has made several specifications, which suggest at what the present system’s problems are. These problems include the problem that the present system does not perform validation checks when the users first enter data. The validation checks should occur on the size and weight of each parcel, as this is what the user enters and therefore may be entered incorrectly. Also the present system cannot update the prices very easily especially as prices are updated in bands of 2kg this information has been deduced from the specification given. The present system is also not able to produce daily management statistics on the number of parcel consignments (also assumed from specification); total weight of the consignments and the total revenue brought in by the consignments. This means that management cannot see the daily progression of the company and find out if and when things are going badly for the company. The present system does not store important data such as the customer identification, parcel destination, the parcel length, breadth, height and weight which is useful when looking at whether customers re use the Postquick parcel company after using it for the first time (this has been deduced from the specification). This type of information could be used for marketing and developing the company's services.

        


OBJECTIVES OF THE NEW SYSTEM

There are several objectives for the new system they include:

  • Validating the parcel consignments. Firstly, validation checks should be run on the pricing of each parcel consignment to make sure the correct price is charged and the customer is not over or under charged as this could result in revenue losses and loss of customers. Validation checks should also be run on each consignment entry using weight, length and total dimension bounds using the clients maximum and minimum bounds as previously specified.

  • Automatically producing a consignment note to accompany the parcel to its delivery destination. The consignment note should be based on the above validation checks.

  • Producing daily statistics on the number of parcels, their origin and destinations, their dimensions, the total weight, and total revenue from the parcel consignments.

  • Easily being able to update prices using a process of calculating the prices in bands of 2kg, the program should then be able to produce a print out of the new price list.


DESIGN

THE FEASIBILITY OF A COMPUTER BASED SYSTEM

It has been required that I should produce a computer based system for the Postquick Parcels company. There are many advantages to a computer based rather than a non-computerised system these advantages include: -

  • Computer systems can be backed up so that if there is a fire or the computers contract a virus, the files are not lost altogether. However if the system was not computerised and there was a fire, the data would be lost. Which could lead to a loss of customer due to a lack to reliability to the customer.
  • A computer system can be modified and changed more easily than a non-computerised system. E.g. if you wanted to change the format of the customer data entry forms on a computer it could be done in a few minutes but manually on a non computerised system it would take a very long time to rewrite the records if they were held on card.
  • A computerised system can find files within seconds where as on a card filing system it would take people a lot longer as it has to all be done by people and then the process is subject to human error.

Going on my recommendation of a computerized system I now have to provide and recommend the hardware and software most suitable for the system.

Hardware

The hardware of a machine is the physical machinery, which makes up the computer. In order to start to think about designing a system I need to first of all think about the possible use of different types of hardware: -

  • Keyboard – used mainly to enter in data about the customer, parcel and the parcels destination.
  • Visual Display Unit – A user-friendly way to display the database system.
  • Digital scales (for weighing parcels) – so weights have been calculated accurately
  • Computer mouse – to select different function options.  
  • Screen Touch Screen – to speed up the input of data and other functions within the database system.
  • Screen pens - to speeded up processes within the system especially the input of data.

I have decided to keep the hardware simple any only have a computer, keyboard, VDU and mouse. This is relatively cheep compared with the other options and will be sufficiently simple for the users to handle.

Choices of Software

There are three main choices of software these are Excel a spreadsheet, Access a database or a high level language such as Pascal. All have advantages and disadvantages.

Excel

Excel has many advantages, which include the following points and features: -

  • Excel allows you to insert buttons or macros these allow you to open and close forms at the click of a button. They also allow you to do things like run a query or calculation.

  • Excel allows you to highlight different cells in colour and fill effects. You can highlight a cell by first clicking on the cell you want and then the fill colour icon, which brings up a range of colour, you can also colour the text or lines.

  • There is a formula bar at the top, which displays the formula of the cell you are viewing; here you can also add things to the formula.

  • You can create look-up tables.

  • You can create graphs using the Chart Wizard tool.

 

  • In Excel you can also copy the cell of a formula from cell you cell. This can be very useful when using a formula to calculate a certain equation.

 

  • You can name cells, which makes identifying cells easier.

  • Excel is a multi dimensional spreadsheet, this means that you can have as many sheets as you want, this is also known as a three dimensional spreadsheet.

Excel has disadvantages as well as advantages, these include: -

  • If you change the name of a page after making a macro it can't find the correct page because it has changed names. This means you then have to go into Visual Basic and manually change the name of the page on the actual piece of code. This all takes time and if you change more than one page’s name it will take a very long time.
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  • With the labels of the graph they will not change with the data so you end up having to go over the whole process of making a graph again.

Access

Access also has its advantages and disadvantages, which need to weigh up against Excel's advantages and disadvantages to come up with the right choice of software. Access' advantages include: -

  • Access can perform advanced queries.

 

  • Access can make forms to insert data.

 

  • Access is very user friendly.

  • In Access you can have macros to go between forms and queries.
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