CSCI 7132: Database Systems Design

database system (DBS)

An electronic record keeping system

What are the four components of a database system?

database (DB)
database management system (DBMS)
hardware
users

Data

A raw fact about an entity or event in the real world

Information

Data that has been processed

In reference to a database, what are the three data types?

input data
output data
persistent data

Input data

Any data that is entering the database

Output data

Any outcome produced by a database in reaction to an input

Persistent data

Data that you cannot 100% delete from a database

What happens if persistent data is removed from a database?

The database collapes and is no longer usable

What are the components of persistent data?

operational data
decision support data

operational data

Data that are subject to operation within the enterprise

decision support data

Data that are simply summaries and generated for
decision making purposes

components of operational data

core data

associate data

core data

Data about the core entities of the organization

core entity

An entity within an enterprise that is one of the focus of the
enterprise activities

How do you know that an entity is a core?

If core entity’s data be removed, then the existence of the database, and the enterprise is meaningless.

associate data

Data used to express the relationship among core entities and/or pieces of core data

database (DB)

An organized collection of persistent data regarding an enterprise

database management system (DBMS)

A software package in charge of providing/supporting a data language and executing the queries issued by users

data language

Computer language helping users express their queries

Sublanguage and stand-alone

The two types of data languages

sublanguage data language

Performs basic database manipulation ONLY

stand-alone data language

Full-grown computer language with statements and includes every action from sublanguage

1. Intercepts query
2. Validates the syntax and semantics"
3. Reports errors (if any)
4. Executes valid query
5. Delivers result to user

How does a database management system execute a query?

Hardware is required to execute the database management system software.

Why is hardware a component of database systems?

end-user
application programmer
database admin (DBA)
data manager

The four types of users of database systems

End-User

An individual who has no knowledge of database but knows how to use a GUI to get a limited set of data from a database

Application Programmer

An individual who has knowledge of the database and knows, at least, one data language and can write programs to manipulate a database

Database Admin (DBA)

An individual (or team of people) who analyze, design, implement, and secure a database

Data Manager

An individual (or team of people) who analyze and design a database when the database is too large

redundancy
sharing
integrity
inconsistency
security
data independence

List the potential issues of database systems

redundancy

Having multiple copies of a piece of data in the database

Why is redundancy bad in a database?

If one copy of the data is updated, then we need to update all copies of data

What are the two types of redudancy?

Controlled
Uncontrolled

What is controlled redundancy?

If a piece of data has multiple copies and the location of every copy inside the database is known to the DBMS, then redundancy is controlled

What is sharing in a database?

The content of a database must be shared among users who have permission to see them

What is concurrency?

A problem introduced by sharing, when more than one user is seeking a datum, a row of a relation, and/or an entire relation at the same time

integrity

The correctness of data that are kept in the database

inconsistency

Data for a given entity is different from one relation to the next

What is security?

Protecting contents within an organization’s database from unauthorized people

What is external security?

Protecting the organization’s database from people that are not employee of the organization

What is internal security?

Protecting the organization’s database from those people who are employee of the organization and can have access to the database

data independence

Immunity of application programs to changes in access method or storage structure

What are the responsibilities of a database admin?

database analysis
database design
database execution
building data dictionary

database analysis

Deciding on the information content of the database
Deciding on the storage structure and access strategy
Collecting user groups’ requests and deciding on the user groups’ views

What is database design?

Adopt a data model and adopt a design paradigm within the adopted data model

What is database execution?

Building, populating, and maintaining the actual database
Enforcing efficient modifications in storage structures and access strategies, if needed
Enforcing Internal and external Security

What is a data dictionary?

An official document about all the database analysis, design, and execution