Quick questions about normalisation (1 Viewer)

honky tonk

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For starters, when you normalise a database, do you end up with two tables - one with a primary and foreign key, and the other with just a primary key?

Secondly, are there two or three types of norms? (Heinemann has 2, Excel has three)

Thanks! :)
 

4130warrior

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You can have more than 2 tables, it depends on the extent of the normalisation and of course the fields and their relationships in the database.

I can't help you with the second question, as I only know of 1FN and DKFN... but Excel is a pretty thorough guide...?
 

honky tonk

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Originally posted by 4130warrior
You can have more than 2 tables, it depends on the extent of the normalisation
Ahhh Ok, so is it right, though, that if you do have two tables, there would be one with a primary and foreign key, and another with just a foreign key?
Originally posted by 4130warrior
I can't help you with the second question, as I only know of 1FN and DKFN
Just in case you were interested, here is what the Excel book says:
  • First Norm Form - Each field in a table contains different information. For example, in an employee list, each table would contain only one date_of_birth field.
  • Second Norm Form - No field values can be derived from another field. For example, if a table already included a date_of_birth field, it could not also include a birth_year field, since this information would be redundant.
  • Third Norm Form - No duplicate information is permitted. So, for example, if two tables both require a date_of_birth field, the date_of_birth information would be separated into a separate table, and the two other tables would then access the date_of_birth information via an index field in the date_of_birth table. Any change to a date_of_birth would automatically be reflected in all tables that link to the date_of_birth table.
Man, after typing that - I'm more confused than ever. :(
 

Huy

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Originally posted by honky tonk
Ahhh Ok, so is it right, though, that if you do have two tables, there would be one with a primary and foreign key, and another with just a foreign key?

Man, after typing that - I'm more confused than ever. :(
If you had two tables:

Table 1: primary key and foreign key
Table 2: foreign key (seen from Table 1), which is actually the primary key (seen from Table 2).

Each table has a primary key, but Table 1 (main/first) table sees or imports the primary key of the second, into a foreign key (by definition).

About the degrees of normalisation, just know 1NF (first norm form) and domain and key normal form (DKNF).

If you're confused, forget it, and stick to the definition of normalisation ;)

Degrees of normalisation is good to know, if you understand it, and if you don't, it won't matter too much, as it's not really tested or assumed knowledge.
 

Huy

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Originally posted by rx72c
Just normalise it aint that hard. MAKE IT NORMAl. are you normal?
This is not like you... :(
 

rx72c

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yeh i know, ive kind of just fallen apart after the hsc, ive been relaxing too much and am missing school alot so im bored. sorry if i annoyed anybody.
 

Huy

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Originally posted by rx72c
yeh i know, ive kind of just fallen apart after the hsc, ive been relaxing too much and am missing school alot so im bored. sorry if i annoyed anybody.
I can see you're bored/fallen apart.

Maybe a little too relaxed.

Relaxed is good though :)
 

rx72c

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hehe, relaxed is good, fallen apart isnt. Dont get a girlfriend, they are annoying, my one cant stop calling.
 

Huy

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*writes that down*

I've never had a gf, so I wouldn't know the difference :p :rofl: :rofl: :D
 

rx72c

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Funny that. Sometimes its good to have a girl friend but sometimes its just damn right annoying and they are always askin you bloody gay questions "do you love me" . GETS VERY ANNOYing.
Im saying this cause i know there aint much girls on this forum and i know i wont get my head bitten off.
 

Huy

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Originally posted by rx72c
Im saying this cause i know there aint much girls on this forum and i know i wont get my head bitten off.
The question really, isn't about whether there are girls on the forum, it's about whether or not there are girls in the IPT forum. Not many hang out in here, so you'll find most in Non-School. :)

These posts are becoming "Non-school" esque.

Maybe we should stop posting in here as a "secret hideout" before something happens. ;) :p
 

Huy

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Originally posted by rx72c
Yeh ill got non school now and show them HAhAHAHA.
See you there, instead of here :)
 

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