A database is a collection of data that can be used alone or combined with other data to answer user questions. A database management system (DBMS) provides programs to manage databases, control access to data, and include a query language to easily retrieve information. It is important to design databases such that a specific item can be easily reached, the database can respond to different user questions, it occupies minimum storage space, and data can be added and updated without errors or redundancy. Proper database design involves requirement analysis, conceptual design using an entity-relationship model, and physical implementation using a DBMS.

1. DATABASE MANAGEMENT SYSTEMSDATABASE MANAGEMENT SYSTEMS
BASIC CONCEPTSBASIC CONCEPTS
1. What is a database?1. What is a database?
A database is a collection of data whichA database is a collection of data which
can be used:can be used:
• alone, oralone, or
• combined / related to other datacombined / related to other data
to provide answers to the user’s question.to provide answers to the user’s question.
N. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 SpringN. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 Spring

2. 2. What is a Database Management System?2. What is a Database Management System?
A DBMS is a collection of programs whichA DBMS is a collection of programs which
• provide management of databasesprovide management of databases
• control access to datacontrol access to data
• contain a query language to retrievecontain a query language to retrieve
information easilyinformation easily
DATABASE MANAGEMENT SYSTEMSDATABASE MANAGEMENT SYSTEMS
N. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 SpringN. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 Spring

3. 3. Database Design3. Database Design
It is important to design the database in such aIt is important to design the database in such a
way that:way that:
• A specific item can be reached easilyA specific item can be reached easily
(maximum guarantee that the desired record will be(maximum guarantee that the desired record will be
reached)reached)
• The database can respond to the user’sThe database can respond to the user’s
different questions easilydifferent questions easily
(necessary relationships are provided)(necessary relationships are provided)
DATABASE MANAGEMENT SYSTEMSDATABASE MANAGEMENT SYSTEMS
N. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 SpringN. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 Spring

4. •The database occupies minimum storage spaceThe database occupies minimum storage space
(choosing data types and how to express a certain(choosing data types and how to express a certain
concept is important)concept is important)
•The database contains no unnecessary dataThe database contains no unnecessary data
(storing the gross salary is enough, the net salary(storing the gross salary is enough, the net salary
can be calculated from the gross salary)can be calculated from the gross salary)
• Data can be added and updated easilyData can be added and updated easily
without causing mistakeswithout causing mistakes
(no data redundancy)(no data redundancy)
DATABASE MANAGEMENT SYSTEMSDATABASE MANAGEMENT SYSTEMS
N. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 SpringN. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 Spring

5. Data redundancyData redundancy
Different and conflicting versions of the same
data
e.g. Employee database:
personal info payroll
- ID - ID (relating parameter)
- name - name (causes redundancy)
- address - gross salary
DATABASE MANAGEMENT SYSTEMSDATABASE MANAGEMENT SYSTEMS
N. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 SpringN. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 Spring

6. STEPS IN DATABASE DESIGNSTEPS IN DATABASE DESIGN
• Requirement analysisRequirement analysis
What does the user want?What does the user want?
• Conceptual database designConceptual database design
Defining the entities and attributes, and theDefining the entities and attributes, and the
relationships between theserelationships between these --> The ER model--> The ER model
• Physical database designPhysical database design
Implementation of the conceptual design using aImplementation of the conceptual design using a
Database Management SystemDatabase Management System
DATABASE MANAGEMENT SYSTEMSDATABASE MANAGEMENT SYSTEMS
N. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 SpringN. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 Spring

7. TERMINOLOGYTERMINOLOGY
• EntityEntity --> What is this table about?--> What is this table about? studentsstudents
• AttributeAttribute (Field) --> What items of(Field) --> What items of
information are necessary to keep concerninginformation are necessary to keep concerning
this entity?this entity?
ID, name, department, year, advisorID, name, department, year, advisor
• RecordRecord (Tuple) --> A set of values for each(Tuple) --> A set of values for each
attribute for one itemattribute for one item
2002765420027654 Ali KayaAli Kaya CAACAA 22 Ahmet DurukalAhmet Durukal
DATABASE MANAGEMENT SYSTEMSDATABASE MANAGEMENT SYSTEMS
N. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 SpringN. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 Spring

8. • KeyKey --> The attribute used to define a required--> The attribute used to define a required
itemitem
who is the advisor ofwho is the advisor of Ali KayaAli Kaya??
Types of keys:Types of keys:
** Primary KeyPrimary Key: Key used to uniquely identify a record: Key used to uniquely identify a record
** Foreign KeyForeign Key: A field in this table which is the Primary: A field in this table which is the Primary
key of another tablekey of another table
• RelationshipRelationship --> Definitions linking two or--> Definitions linking two or
more tablesmore tables
DATABASE MANAGEMENT SYSTEMSDATABASE MANAGEMENT SYSTEMS
N. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 SpringN. Fenmen - CAA292 Database Applications for Business - 2003 - 2004 Spring