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Database Environment - Coggle Diagram
Database Environment
three-level architecture
External level: The users’ view of the database. This level describes that part of the database that is relevant to each user
Conceptual level: The community view of the database. This level describes what data
is stored in the database and the relationships among the data
Internal level: The physical representation of the database on the computer. This level describes how the data is stored in the database.
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DDL
A language that allows the DBA or user to describe and name the entities,attributes, and relationships required for the application, together with any associated integrity and security constraints.
DML
A language that provides a set of operations to support the basic data manipulation operations on the data held in the database
Procedural DML
A language that allows the user to tell the system what data is needed and exactly how to retrieve the data
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Data model
An integrated collection of concepts for describing and manipulating data, relationships between data, and constraints on the data in
an organization.
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manipulative part
defining the types of operation that are allowed on the
data (this includes the operations that are used for updating or retrieving data from the database and for changing the structure of the database
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Functions of a DBMS
(1) Data storage, retrieval, and update
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Forms generators :
A forms generator is an interactive facility for rapidly creating data input and display layouts for screen forms.
Report generators :
A report generator is a facility for creating reports from data stored in the database.
Graphics generators :
A graphics generator is a facility to retrieve data from the database and display the
data as a graph showing trends and relationships in the data
Application generators :
An application generator is a facility for producing a program that interfaces with
the database. The use of an application generator can reduce the time it takes to
design an entire software application
Universe of Discourse (UoD);
an external data model, to represent each user’s view of the organization
Physical Data Models:
Physical data models describe how data is stored in the computer, representing
information such as record structures, record orderings, and access paths
Conceptual modeling or conceptual database: design is the process of constructing a model of the information use in an enterprise that is independent of implementation details