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**oblivion_6** · 09-01-2006, 13:31

Ah databases my forte

http://www.bkent.net/Doc/simple5.htm - Normalisation link
Normalisation is basically you just trying to make sure that your tables dont repeat information and if there are anythings which can occur several times with different results then they should be in a seperate table

Entity relationships should come after youve normalised as then you will work out exactly all your table names

E.g. Univeristy Course would consist of the teach entity which would be related to the Class entity, now 1 teach could teach many classes and many teachers could teach many classes so you need something inbetween the two to stop the many:many

This would be something like TeacherClassAppointment, this could have a teacher ID which would point to the teacher entity and a class id which would point to a specific class in the class entity

You can see where this is going....you could have a ClassRota table which would have a TeacherClass ID and a student ID this would link the student entity with the class and teacher id which would allow you to see the class and teacher teaching each student

Its hard to explain without drawing a wee diagram but if you need more send me a pm

**bangaio** · 09-01-2006, 15:49

Supergoal, what sylabus / course are we talking about here. I ask only as I am an (still in training) ICT teacher so may be able to help you out, I did lots of work in my last school with AS/A2 students doing the AQA ICT course. I do also have a link to recomend for a great normalisation book written in pretty easy to understand terms with loads of worked examples by another ICT teacher, costs about a fiver, i'll put it up here when I find it!

**Supergoal** · 09-01-2006, 16:01

A2 ICT I'm doing.

**bangaio** · 09-01-2006, 16:24

ok, cool. I'd say, first speak to your teacher! Second, remember that as far as normalisation goes, it's a very methodical (and dull) process so work whtough loads of examples step by step. Don't try and be clever and jump from 0NF to 3NF, you'll just make life very very hard for yourself. Remember the principal of normalisation and ERD is to make your database model as efficient as possible. If you have worked examples of say a school or library (dull I know) or something similar try to apply the same principles to your own system.

This book rocks: http://www.theteacher.info/products/Normal/normal.html Get your teacher tyo get it and if they won't, get it yourself.

Here's a little tip to remember the three stages -

Each attribute is dependent on the key, the whole key, and nothing but the key!

So, to get to third normal form, your non-repeating fields (first normal form) need to be dependent on the whole of the key (second normal form), and nothing other than the key (third normal form).

The best way of looking at dependencies is to always ask youself when looking at a group; "could I find this from my database by giving it these pieces of information".

errrr what else, it's going to be kind of hard to explain online and is best taught I personally believe. I've spent at least two hours on it with an A2 class in the past so make sure you ask for help, it's what your teacher's there for!

**Supergoal** · 09-01-2006, 16:55

Thanks for the advice. I have already made a database and was at the point of testing only to find out it didn't do what I wanted it to do!
Seems like my tables are wrong.

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