380%20Sum11%20Cl2%20Normalization%20HO

380%20Sum11%20Cl2%20Normalization%20HO -...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Click to edit Master subtitle style 380 Mtg 2 – Normalization Normalization concepts Normalization Practice To Dos
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Muddiest Points
Background image of page 2
Input Data to Bits and Bytes
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
The Business Problem… Many applications → many data files Examples? Implications?
Background image of page 4
Data Storage Difficulties Storing data is Prone to fragmentation, duplication/redundancy, which in turn leads to inconsistency between them » Data “Integrity” Important » Often the data IS the business Examples? Expensive to store data » Needs growing faster than price is dropping How to store data effectively, cheaply?
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
The Solution… Create Databases to enable info sharing But how do you design/implement them? » Bottom Up approach – Normalization Take existing data fields and store them in most efficient way possible » Top Down approach via Data Modeling Develop a database based on Logic/theory, then translate into a physical database Today
Background image of page 6
Terms - Data Hierarchy Field 1 Field 2 Field 3…. Record File One or more related files-a Database 1 Byte Bit→Byte →Field →Record →File →Database
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Normalization of Physical DB A means of storing data to eliminate duplication First normal form (1NF) Second normal form (2NF) Third normal form (3NF) Fourth normal form (4NF or BCNF) – we won’t address Cumulative i.e. 3NF includes 2NF; 2NF includes 1NF You must create 3NF (1NF, 2NF don’t get marks)
Background image of page 8
Normalization Example See example of an Invoice database kept in Excel
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Normalization Defined “Normalization usually involves dividing a database into two or more tables and defining relationships between the tables. The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database via the defined relationships .” - Webopedia, http://webopedia.internet.com/TERM/n/normalization.html
Background image of page 10
The Normal Forms A series of logical steps to take to normalize data tables » First Normal Form – “The Key” - Eliminate repeating groups to create one table » Second Normal Form – “The whole key” - Create new tables so main table is left only with fields that depend on its entire primary key » Third Normal Form – “Nothing but the key” - Create new tables so new tables are left only with fields that depend on their entire primary key
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
1NF - First Normal Form 1. Eliminate repeating attributes (columns) that are missing data by turning them into rows 2. Ensure each row has a unique identifier (‘Primary Key’) Could be one, or a combination of, columns (e.g. Invoice #, Item #) Yields a perfectly rectangular spreadsheet i.e.
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 39

380%20Sum11%20Cl2%20Normalization%20HO -...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online