database management system presentation

BASIC CONCEPTSBASIC CONCEPTS

1. What is a database?1. What is a database?A database is a collection of data which A database is a collection of data which can be used: can be used: • alone, or alone, or • combined / related to other data combined / related to other data to provide answers to the user’s question.to provide answers to the user’s question.

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 databases provide management of databases • control access to datacontrol access to data• contain a query language to retrieve contain a query language to retrieve information easily information easily

3. Database Design3. Database DesignIt is important to design the database in such a It is important to design the database in such a way that:way that:

• A specific item can be reached easily A specific item can be reached easily (maximum guarantee that the desired record (maximum guarantee that the desired record will bewill be reached) reached)• The database can respond to the user’sThe database can respond to the user’s different questions easily different questions easily (necessary relationships are provided)(necessary relationships are provided)

DATABASE MANAGEMENT SYSTEMSDATABASE MANAGEMENT SYSTEMS

•The database occupies minimum storage spaceThe database occupies minimum storage space (choosing data types and how to express a (choosing data types and how to express a certaincertain 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 (storing the gross salary is enough, the net salarysalary 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 mistakes without causing mistakes (no data redundancy)(no data redundancy)


Data redundancyData redundancyDifferent 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


STEPS IN DATABASE DESIGNSTEPS IN DATABASE DESIGN• Requirement analysis Requirement analysis What does the user want?What does the user want?• Conceptual database designConceptual database designDefining the entities and attributes, and the Defining the entities and attributes, and the relationships between these relationships between these --> The ER model --> The ER model • Physical database designPhysical database designImplementation of the conceptual design Implementation of the conceptual design using a Database Management System using a Database Management System


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 concerning information 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 item2002765420027654Ali KayaAli Kaya CAACAA 22 Ahmet DurukalAhmet Durukal


• Key Key --> The attribute used to define a required --> The attribute used to define a required itemitem

who is the advisor of who 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 table key of another table

• Relationship Relationship --> Definitions linking two or --> Definitions linking two or more tables more tables


database management system presentation

Education