DBMS architecture describes the structure and how the users are
connected to a specific database system.
The DBMS architecture is divide into three levels.
(i) External level
(ii) conceptual level
(iii) Internal level
External level External view
External & conceptual mapping
Conceptual & internal mapping
External level:- The external level is closed to the user that is one constant in which data
Conceptual level:- It describes how the database appears to the users conceptually and
the relationships between various data tables.
Internal level:- It describes the actual physical storage of data or the way in which the
data is actually stored in memory.
4. What is three-tier
A THREE-WAY INTERACTION IN A CLIENT/SERVER
The user interface is stored in the client.
The bulk of the business application logic is
stored in one or more servers.
The data are stored in a database server.
3 Tier client server architecture
Server:- A server system that takes a client
request and returns a response.
DBMS:- before accessing the database server it
checks a lot of info so that it does not appear.
The goal of Three Tier client-server architecture is:
•To separate the user applications and physical database
•To support DBMS characteristics
•Supporting multiple views of the data
A data model is set of concepts that can be used to
describe the structure of data in a data base.
A data base show the logical structure of a data base
including the relationship and constraints that
determine how data can be stored and accessed.
Data models are use to support the development of
information systems by providing the definition and
format of data to involved in futures systems.
Data models also gives ideas about possible alternatives
to achieve targeted solution.
Types of data models
1. Hierarchial model
2. Network model
3. Relational model
9. Hierarchial model 9
This model developed by BY IBM and north
American rockwell known as information
This is the oldest and simplest DBMS model.
The model is sorted hierarchical , either in top
down or buttom up approach of designing.
This model uses pointers to negative between
11. Advantages of hierarchical model
1. conceptual level
Relationship between various level is
logically very simple. Hence database
structure becomes easier to view.
2. Database security
Security is given by DBMS system itself.
12. Disadvantages of hierarchical
complex of implementation
programmers and designers need to have knowledge of physical data
storage which may be complex.
2. Difficult to manage.
Any change in a location of data needs change In all application
programs that accesses changes data.
Data access is restricted by pointer.
13. Network model
This model is hierarchical model, this model also uses pointers toward
data but there is no need of parent to child association.
It uses graph data structure.
A child can have more than one parent.
It has one to many or many to many relationship.
A relationship between any two record types is called as a set.
Data in network model are represented by collection of records and
relationship among data are represented by links.
The records in the database are organized as collection of bitrary
15. Relational model
The relational model is first proposed by E.F cod.
This model uses collection of tables to represent relationship
among the data.
In this model is database item is viewed as a record with
attributes a set of records with similar attributes is called a
TABLE. Each table contains a record of a particular type.
The database uses relationship model called as RDBMS.
A relation database is a collection of 2-D tables which
consists of rows and columns.
16. Relational model is the most popular model and the
most extensively used model.
In this model the data can be storage in the tables and
this shorting is called as a relation the relationals can be
normalized and the normalized relation values are called
Each row in a relation contains unique value and it is
called as triple each column contains value from same
domain and it is called as attribute.
Most of the popular commercial DBMS product like
Oracle mySQL are based on relational model.