Databases and database users Flashcards
Define what a database is.
A database is a collection of related data with an implicit meaning.
What do we mean by data?
By data we mean known facts that can be recorded and that have an implicit meaning.
What are the database’s implicit properties?
- A database represents some aspect of the real world,
sometimes called the miniworld or Universe of
Discourse (UoD).Changes on the miniworld are
reflected onto the database. - A database is a logically coherent collection of data
with some inherent meaning. - A database is designed, built, and populated with data
for a specific purpose.
What is a Database Management System (DBMS)?
Is a computerized system that enables users to create and maintain a database. The DBMS is a general-purpose software system that facilitates the processes of defining, constructing, manipulating, and sharing databases among various users and applications.
Explain the defining process.
Defining a database involves specifying the data types, structures, and constraints of the data to be stored in the database. This information is stores as meta-data in the catalog.
Define the constructing process.
Constructing the database is the process of storing the data on some storage medium controlled by the DBMS.
Define the manipulating process.
Manipulating a database includes functions such as querying the database to retrieve specific data, updating the database to reflect changes in the miniworld, and generating reports from the data.
What is a query?
A query typically causes some data to be retrieved; a transaction may cause some data to be read and some data to be written into the database.
Describe the protection function of a DBMS.
Protection includes system protection against hardware or software malfunction (or crashes) and security protection against unauthorized or malicious access.
Describe the maintaining function of a DBMS.
The database system is maintained by allowing the system to evolve ad requirements evolve over time.
Define the process of creating a new application.
- Requirements specification and analysis phase. The
requirements are documented in detail and
transformed into a conceptual design. - The design is then translated to a logical design that
can be expressed in a data model implemented in a
commercial DBMS. - The final stage is the physical design, during which
further specifications are provided for storing and
accessing the database.
What are the main characteristics of the database approach versus the file-processing approach?
- Self-describing nature of the database system.
- Insulation between programs and data, and data
abstraction. - Support of multiple views of the data.
- Sharing of data and multiuser transaction processing.
What is the self-describing nature of the database system?
The information stored in the catalog is the meta-data, which describes the structure of the primary database.
NOSQL systems, do not require meta-data. The data is stored a a self-describing data.
Describe the property of program-data independence.
Due to the fact that the structure of data files is stored in the catalog separately from the access programs, the DBMS access programs don’t need to be changed.
What characteristic allows for program-data independence?
This characteristic is data abstraction. A DBMS provides users with a conceptual representation that doesn’t include any details about how the data is stored. Hence the data model hides storage implementation details that are of no interest to most database users.
