Techie Stuff

Database - Planning your Access Database

Take time with Planning

It's quite common to feel daunted at planning how to lay out your database ~ especially if you are not sure about normalization and how how to separate out unrelated information.

This is partly because of the type of paper forms that we are used to dealing with - with all different kinds of information there on the same form.

If you think about the hand writing (or typing) involved in filling-out a paper form, you can see that you might want to 'double up' on as much information as possible. This was a great way to save time and effort, but it has been responsible for some very disorganized and unwieldy forms in its time!! When filling in a form in a database, you really don't need to keep typing-in that same information again and again and so this is your big opportunity to start to separate out the types of information.

It's probably not a good idea to try to plan your database based on a paper form. Instead make a list of the 'fields' on your form and then put the form on one side (you can come back to it later on in the course, when you are ready to start creating forms). Once you have the list of fields you can start to separate them out into distinct tables where only information that is related is included. This may well mean making several tables and this can be disconcerting for the beginner.

Remember: On a paper form you would have put all the different kinds of information on the same sheet .. but you would still have thought about the different kinds of information in different ways. (Humans do this so automatically and instinctively that it takes a little bit of thinking about to realize that you're doing it at all!)

When creating a database it's important to separate out different kinds of information. So for instance you might want to create a database to hold employee identity numbers as well as their names. So you create a table with those fields. Now it's tempting to starting adding other fields (like for instance their manager's name, their current salary, their office location) all into the same database. It may seem very useful at the time, but it may well cause problems later on. You are certainly going to find it gets unwieldy. So you must create separate tables for separate kinds of information and then you can create relationships between those tables which would represent how the information 'fits together'.

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Kathie Kingsley-Hughes
Last updated: May 4th 2004
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