Disputed Subjects (1 Viewer)

[Mercurial]

Sup pplz, if u got some disputed upon or controversial questions juz bring it on.

I have one.

Wats is normalising in databases?

I've checked through several scources and recieved different answers. Eg. It is the elimination of data redundancy by organising the data into tables as in relational dbs.
However, another explanation states, it is the removal of redundant links. That is, reconstructing the relationships of a db so that daughter dbs r directly linked to parent ones as to reduce CPU time with operations (like querying).

Pleez help us out here.

 

[esther]

it says in the usyd notes that normalising is analysing the data to produce the most effiecient database structure. This includes:
- eliminating data redundancy by removing repeated fields
- creating several tables and carefully defining the relationships between them.
Thus ambiguities should be removed and any changes that need to be made over time to the database need only be made once due to the relationships set up

 

[Mercurial]

Wow, so kool.

So it was like both of them put together sorta. Thnx.

 

[googy_1985]

In the CSSA trial, it has
Identify the most accurate description of the process of normalisation.

A) Fixing any irregularities in a relational database
B) Process of disorganising data in a database.
C) Process of removing inconsistent data redundancy
D) Process of organising data in a database.

 

[googy_1985]

Their answer was D.

Is it possible u could also put C???

 

[Morgues]

I dont think normalisation actually removes redundancy........its more like it organises into seperate tables to make the redundancy more meaningful although some text books do mention its main purpose is to remove data redundancy

 

[user]

how can you have an inconsistent data redundancy? It's either there or not, you either have it or don't.

 

[Mercurial]

I hate multiple choice... its gay.

I know wat u mean though. But from Esther's explanation,
"creating several tables and carefully defining the relationships between them."
It seems that it has more to do with organising data in a db. The result of which might b the removal of data redundance.

 

[Mercurial]

Okay, this ones for the software ppl.

When constructing SQLs the structure goes as the following:
SELECT
FROM
WHERE
ORDER BY

However, the textbook is ambigious with the syntax for FROM. I know that it is the scource of the data but does this require the tables they fields came from or tables and attributes?

I have a feeling they r gonna ask it in the trials. Juz cuz i dont know it.

 

[trivonovsky]

The FROM command is just the table or tables that the fields you are searching are coming from.

An example is that you might have a table called "PrimeMinisters" with the fields "FirstName", "LastName", "D.O.B."
and "Party".

If you want the first name and last name fields displayed and you are searching for prime ministers with the last name Howard the search would be.

SELECT FirstName, LastName
FROM PrimeMinisters
WHERE LastName = "Howard"

 

[Mercurial]

hey hey...

thnx buddy. All so clear now.