1. File and data base concepts
DB design

2. File Concepts DATA REPRESENTATION bits and bytes EBCDIC and ASCII
field or data element
record
file or table
data base
FILE ORGANIZATION
sequential
indexed sequential
direct
FILE PROCESSING
batch vs immediate
online vs offline

4. DB: a set of entities and relations
In city
In state
Street
Cities
States
located
Registered on in
Cars
Houses
In country
Occupied
Owned
Has by by
color
Citizen of
Colors
Persons
Countries
Country
of origin

5. DB: subsystems DB logical structures: hierachical network relational
DBMS
DDL OS
DBM
User
Data
Base
DML
Application
program
DB logical structures:
hierachical
network
relational

6. Views, Schema and Subschemas1 2 5 4 7 9 10 8 15 12 17 13

7. DB Design concepts: ... how to represent entities and relations
Flat files
... P#
PNAME
COLOR
WEIGHT
PROJ#
PROJNAME S#
QTY
PROJ# S#
SNAME
STATUS
CITY
DB tables
graphical S S#
SNAME
STATUS
CITY
FIELDS: P P#
PNAME
COLOR
WEIGHT
keys and atributes
primary and foreign keys J
PROJ#
PROJNAME
CITY O S# P#
PROJ#
QTY
relational notation
S (
S#,
SNAME,STATUS,CITY)
P ( P#
,PNAME,COLOR,WEIGHT)
J (
PROJ#
,PROJNAME,CITY)
O (
S#,P#,PROJ#
,QTY)

8. Entities and relations
RELATIONS: one-to-one
one-to-many
many-to-many
Product
a supplier
can provide
project
product can
a product
can use
be part of
can have
Supplier
Project
a supplier
can supply
a project
can have

9. DB Design principles NORMALIZATION:
1. represent each ENTITY as a TABLE
2. select the PRIMARY KEY
3. assign entity ATTRIBUTES to FIELDS
4. represent an ONE-TO-MANY relation by a FOREIGN KEY in the MANY table.
5. represent MANY-TO MANY relations as a NEW TABLE. Use FOREIGN KEYS to identify entities involved. The combination of foreign keys is the PRIMARY KEY of the new table. Assign the common attributes to fields.

10. DB design example Product Project Supplier many many a supplier
can provide
project
product can
a product
can use
be part of
can have
many
many
Supplier
Project
a supplier
can supply
many
a project
many
can have
S (S#,SNAME,STATUS,CITY)
P (P#,PNAME,COLOR,WEIGHT)
J (PROJ#,PROJNAME,CITY)
O (S#,P#,PROJ#,QTY)