DBS201: Normalization Review

Agenda

Steps of Normalization

Bottom Up Database Design

Bottom Up Provided with views of data Views can be screen shots or reports (printouts) Views contain fields (data) Need to groups fields together – find fields that are

in common Result is tables

Normalization

Works through a series of stages called normal forms:

Normal form (1NF)Second normal form (2NF)Third normal form (3NF)

First Normal Form

1. Eliminate repeating groups Present data in a tabular format, where each cell

has a single value and there are no repeating groups

Eliminate repeating groups by eliminating nulls, making sure that each repeating group attribute contains an appropriate data value

2. Identify candidate primary key Primary key must uniquely identify attribute

values (a row)3. State table structure (will show functional

dependencies)

First Normal Form

Identify candidate primary key Identify an attribute who’s value is

different in each row, or Look for any pair of attribute which when

concatenated produce a unique value

First Normal Form

Identify candidate primary key Primary key must uniquely identify attribute values (a row) What is a candidate for primary key in the following?

AttribA AttribB AttribC AttribD AttribE AttribFQQQO WWWO EEEO RRRO TTJO YVYOQQOQ WWVO FEFO RRPO TJTO YYVO QOQQ

WVWO FEEO RPRO JTTO VYYOQOOQ VWWO EFEO PRRO JJTO VYVOQOQO WWWO FEFO PPRO JTJO YYYOQQQO VWVO EEFO PPRO TJJO VYVO

First Normal Form

Identify candidate primary key What is a candidate for primary key in the

following?

AttribA AttribB AttribC AttribD AttribE AttribF

QQQO WWWO EEEO RRRO TTJO YVYOQQOQ WWVO FEFO RRPO TJTO YYVO QOQQ WVWO FEEO RPRO JTTO VYYOQOOQ VWWO EFEO PRRO JJTO VYVOQOQO WWWO FEFO PPRO JTJO YYYOQQQO VWVO EEFO PPRO TJJO VYVO

Only atttribE is a candidate – because it’s value is different in each row

First Normal Form

Identify candidate primary key Primary key must uniquely identify

attribute values (a row) What is a candidate for primary key in the

following?

A B C D E

Horse 2 years $500,000 Mohawk Race Track Lightening Rod

GreyHound 3 years $125,000 Tampa Florida Speckled Speed

Horse 1 year $80,000 Blue Bonnet Raceway Slow Harry

GreyHound 4 years $125,000 Hialia Atlantic City All Leggs

First Normal Form

Identify candidate primary key Primary key must uniquely identify

attribute values (a row) What is a candidate for primary key in the

following?

A B C D E

Horse 2 years $500,000 Mohawk Race Track All Leggs

GreyHound 3 years $125,000 Tampa Florida Speckled Speed

Horse 1 year $80,000 Blue Bonnet Raceway Slow Harry

GreyHound 4 years $125,000 Hialia Atlantic City All Leggs

First Normal Form

What is a candidate for primary key in the following?

Award Player Name

Player Number Position Team Year

Best Defense Joe Wall 17 Left Defense Toronto 1999

Sy Stopp 7 Right Defense Detroit 2000

Pete Puck 22 Left Defense Montreal 2001

Joe Wall 17 Left Wing Toronto 2002

Most Valuable Sam Scores 18 Center Chicago 1999

Wayne Gretzky 99 Center New York 2000

Joe Wall 17 Left Wing Toronto 2002

First Normal Form

What is a candidate for primary key in the following?

Award Player Name Player Number Position Team Year

Best Defense Joe Wall 17 Left Defense Toronto 1999

Best Defense Sy Stopp 7 Right Defense Detroit 2000

Best Defense Pete Puck 22 Left Defense Montreal 2001

Best Defense Joe Wall 17 Left Wing Toronto 2002

Most Valuable Sam Scores 18 Center Chicago 1999

Most Valuable Wayne Gretzky 99 Center New York 2000

Most Valuable Joe Wall 17 Left Wing Toronto 2002

First Normal Form

What is a candidate for primary key in the following?

Team + Year…………No

Position + Team……..No

Position + Year………No

PNumber + Position….No

PNumber + Team…….No

PNumber + Year……..No

PlayerName + PNumber …No

PlayerName + Position……No

PlayerName + Team………No

PlayerName + Year……….No

Award + PlayerName……..No

Award + PNumber………...No

Award + Position………….No

Award + Team…………….No

Award + Year……………..Yes

Second Normal Form

1. Identify partial primary keys2. Determine which attributes are dependent on

the partial primary key3. State table structures (will show partial

dependencies) Write each table structure on a separate line with

it’s primary key Write the original (composite) key on the last line

with attributes removed that have been moved to the new table structures

Third Normal Form

1. For every transitive dependency, identify the determinant – it will be taken from a non-key attribute (will become the PK for a new table)

2. Determine which non-key attributes are dependent on this new primary key

3. State table structures (will show transitive dependencies) Write each table structure on a separate line with

it’s primary new key Write the partial dependency table structures Write the original (composite) key on the last line

with attributes removed that have been moved to the new table structures

Third Normal Form

1. For every transitive dependency, identify the determinant – it will be taken from a non-key attribute (will become the PK for a new table)

2. Determine which non-key attributes are dependent on this new primary key

3. State table structures (will show transitive dependencies) Write each table structure on a separate line with

it’s primary new key Write the partial dependency table structures Write the original (composite) key on the last line

with attributes removed that have been moved to the new table structures