This document provides an overview of a computer project on database systems. It discusses the different levels of a database architecture including the external, conceptual, and internal levels. It also describes key database concepts such as logical and physical data independence, different data models including relational, network and hierarchical, as well as advantages and disadvantages of database management systems.

1. 12TH CLASS Project
COMPUTER PROJECT

2. A PROJECT REPORT ON
Under Guidance Of –
Swati Srivastav
Submitted By –
Varsha Sharma

3.  A database system is basically a computer based
record keeping system. The collection of data
usually reffered to as the database contain the
information about one particular enterprise. It
maintains any information that may be necessary
to the decision making process involved in the
management of that organisation.

4. Abstraction level
EXTERNAL LEVEL
VIEW 1
VIEW 2
VIEW 3
CONCEPTUAL LEVEL OR LOGICAL LEVEL
INTERNAL LEVEL OR PHYSICAL LEVEL

5. CONCEPTUAL OR LOGICAL LEVEL
What data is stored in the data base and what relationship exists between
the data.
EXTERNAL LEVEL
The external or a view level is at the highest level of architecture where
Only those portion of data base concern to the user or a application
Program are include.

6. SCHEMA
The Complete and overall design of data base is called
schema.
SCHEMA
PHYSICALLOGICAL

7. DATA INDEPENDENCE
LOGICAL DATA
INDEPENDENCE
PHYSICAL DATA
INDEPENDENCE

8. PHYSICAL DATA INDEPENDENCE
Physical data inepenence that the physical storage structure or
a device use for storing the data would be changed without
neccesisting a change in the conceptual view or any other
extrnal vie. The change would be observed that mapping
between the conceptual an the internal schema.

9. DATA MODEL
1. RELATIONAL
DATA MODEL
3. HIRARECHAL
DATA MODEL
2. NETWORK
DATA MODEL

10. RELATIONAL DATA MODEL
In the relational data model is base on the collection of table(relation
the user of D.B) system may query these table isert a new tuple,
delete a tuple an modify a tuple.
NETWORK DATA MODEL
In this datamodel is differ from the relational model in that it is
represented by a collection of records. And the relationship exist the
data are represented by link.
HIRARECHAL DATA MODEL
In this data model is represented the relationship among its record
through parent,child relationship and that can be easily represented
through a tree like structure.

11.  Centralise control of data.
 Reduction of redundency.
 Share data.
 Integrity.
 Security.
 Data independence.

12.  Cost of software & hardware increases.
 Complexity of backup store & recovery.
 Need for increase staff.
 Difficulty of handling transaction.
 Large transaction volume.