Define a Database
an organised collection of related data
Define a database Management System (DBMS)
software that manages and controls access to the database
Define a Database Application
a program that interacts with the database at some point in its execution
Define a database system
a collection of programs that interacts with the database
Give an example as a super market as a database
Define an entity
what we store the data about
e.g. a person, an order etc
Define an attribute
for example if the entity was a person the attributes would be for example their hair colour their name etc. they describe entities
What is a file based system
A collection of application programs that perform services for the end- users. Each program defines and manages its own data.
What is a database system
A shared collection of logically related data and its description, designed to meet the information needs of an organisation.
What are the advantages of the file based approach
User control
- end users has total control of the stored data
- Can modify application or data at will
Applications and data file can be optimised for particular tasks
What are the disadvantages of file based approach
- DAta duplication\
- data dependence
- incompatible file formats
proliferation of application programs (APPS)
Explain data duplication
- Each student record is duplicated in each of the three files
- Integrity of students records may be compromised if the files are not all updates
Explain data dependence
suppose the university registrar wishes to record additional information:
any changes to data leads automatically to application program modification
Explain incompatible file formats
different application programs and data files may be incompatible
Define Database management system
A DBMS is a software system that enables the user to define, create, maintain, control access to the database
How does the database approach address this elimitations
- A shared database satisfying the requirements of the three officials is created
- Access to this database is through a database management System (DBMS)
- When the officials need info from the database, they write queries in a special language (SQL) to communicate with the DBMS
- They pass these queries to the DBMS which queries the database on their behalf and returns the results they require
How would you get more information about data files
add more application programs to handle the new quires
What are the roles in data base environment
- Data base administrator
- Database besigner
- application developer
- end user
What is the role of the application developer
Use a programming language (such as Java or C++) to provide the required
functionality for the end-users.
Database administrator
responsible for implementation and monitoring of the database
What is the role of the end user
run applications to perform specific database operations
Name a few advantages of DBMS
Control of data redundancy
* Data Consistency
* Sharing of Data
* Improved data integrity
* Improved Security
* Enforcement of Standards
* Economy of Scale
* Balance of conflicting requirements
* Improved data accessibility and responsiveness
* Increased Productivity
* Improved maintenance through data independence
* Increased concurrency
* Backup and Recovery services
Explain how data redundancy is an advantage of DBMS
Since all data is now stored in a single database, there are no unnecessary multiple copies of some data
Explain how data consistency is an advantage of DBMS
Since only one copy of each data item is stored, then any changes to the data item needs to be done on only one item
