Lesson 2: Database Environment
It is the way in which the data in a database is viewed by users
DBMS architecture
It sets standard for American goods
American National Standards Institute (ANSI)
Three Level ANSI-SPARC Architecture:
It is the uppermost level in the database that allow users to access a customized version of the data in your data base
The External Level (User Representation of Data)
Three Level ANSI-SPARC Architecture:
It tells how the database was structured logically
The Conceptual Level (Holistic Representation of Data)
Three Level ANSI-SPARC Architecture:
The lowest level in a three-tiered database that deals with how the stored data on a database is represented to the user
The Internal Level (Physical Representation of Data)
The skeleton structure that represents the logical view of the entire database
Database Schema
3 different types of schema:
it is the highest level and also called subschemas that correspond to the different views of the data
External Schema
3 different types of schema:
It describes all the entities, attributes, and relationships
together with integrity constraints.
Conceptual Schema
3 different types of schema:
is the complete description of the internal model, containing the definitions of stored records, the methods of representation, the data fields, and the indexes and storage structures used.
Internal Schema
A state of operational database with data at any given
time.
Database Instance
A descriptive language that allows the DBA or user to describe and name the entities required for the application and the relationships that may exist between the different entities. Used to specify the database schema.
Data Definition Language
A language that provides a set of operations to support the
basic data manipulation operations on the data held in the
database.
Data Manipulation Language
Data manipulation operations usually include the following:
insertion of new data into the database
modification of data stored in the database.
retrieval of data contained in the database
deletion of data from the database.
Types of Data Manipulation Language:
A language that allows the user to tell the system what data is needed and exactly how to retrieve the data.
Procedural DML
Types of Data Manipulation Language:
A language that allows the user to state what data is needed rather than how it is to be retrieved.
Non Procedural DML
It is essentially a shorthand programming language. It encompasses the Presentation languages, such as query languages and report generators.
4GL (Fourth-Generation Language)
It is an interactive facility for rapidly creating data
input and display for screen forms.
Form Generators
It is a facility for creating reports from data stored in
the database.
Report Generators
It is a facility to retrieve data from the database
and display the data as a graph showing trends and relationships in
the data.
Graphic Generators
It is facility for producing a program that interfaces with the database.
Application Generators
Select at least 3 functions of DBMS
Data storage, retrieval, and Update
A user-accessible catalog
Transaction support
Concurrency control services
Recovery services
Authorization services
Support for data communication
Integrity Services
Services to promote data independence
Utility services
Components of DBMS:
It can range from a single personal computer to a single mainframe or a network of computers.
Hardware
Components of DBMS:
It comprises the DBMS software itself and the application programs, together with the operating system, including network software if the DBMS is being used over a network.
Software
Components of DBMS:
most important component of DBMS environment from the end-users pov is the data
Data
Components of DBMA:
It refers to the instruction and rules that govern the design and use of the database.
Procedures
Components of DBMS:
The final component is the people involved with the system.
People
MULTI-USER DBMS ARCHITECTURES:
Traditional architecture for multi-user systems
Teleprocessing
MULTI-USER DBMS ARCHITECTURES:
The processing is distributed about a network, typically a local area network (LAN).
File-Sever Architecture
MULTI-USER DBMS ARCHITECTURES:
Refers to the way in which software components interact to form a system.
Client server architecture
Traditional Two-Tier Client-Server Architecture:
Manages user interface and runs application
Client (tier 1)
Three-Tier Client-Server Architecture:
_____ client, requiring considerable resources on client's computer to run effectively.
Fat
Three-Tier Client-Server Architecture:
_____ client side administration overhead
Significant
Traditional TWo-Tier Client-Server Architecture:
Holds database and DBMS
Server (tier 2)
A programs that controls data transfer between clients and server in order to provide a consistent enviroment, particularly for online transaction processing (OLTP).
Transaction Processing Monitors