2. Problems with file processing systems
Inconsistent data
Inflexibility
Limited data sharing
Poor enforcement of standards
Excessive program maintenance

3. Levels of Data
Character :The most basic logical element is character.Which
consists of alphabetic, numeric or other symbol.
Field : It consists of grouping of characters.For example, the
grouping of alphabetic characters.For example grouping of
alphabetic characters in a person’s name form a name field.
Record :Related fields of data are grouped to form a record.
File :A group of related records is a data file, or table.
Database :The highest level in the hierarchy is the database.A
database is an integrated collection of logically related records or
files.

4. Objectives of Data Base
Controlled Redundancy
Ease of learning and use
Data independence
Accuracy and Integrity
Privacy and security
Shared
Recovery from failure
Performance

5. Types of Data Bases
Operational Data Base
Analytical Data Base
Data Warehouse Data Base
Distributed Data Base
End User Data Base
External Data Base

6. Operational Database
Data Bases store detailed data needed to support operations of
entire organization
They are also called Subject Area Databases ,transaction
database and production database
A customer database, inventory database, and other database
containing data generated by business operations

7. Analytical Database
Databases store data extracted from selected operational and
external databases
Consists of data mostly needed by an organization’s managers
and other end users
They are also called management databases or information
databases
They are the databases accessed by the online analytical
processing (OLAP) systems, decision support systems and
executive information systems

8. Data Warehouse Databases
Stores data from current and previous years that has been
extracted from various operational and analytical databases of
an organization
It is a central source of data that has been standardized and
integrated so it can be used by managers and other end user
professionals throughout an organization

9. Distributed Database
Databases of local work groups and departments at regional
offices, branch offices, manufacturing plants and other work
sites
Can include segments of common operational and common
user databases as well as data generated and used only at a
user’s own site
Ensuring that all the data in distributed databases are
consistently and concurrently updated

10. End User Database
These databases consist of a variety of data files developed by
end users at their workstations
For example, users may have their own electronic copies of
documents they generated with word processing packages or
received by electronic mail.

11. External Database
Access to external online databases or data banks is available
for a fee from commercial information services , or for free of
price from many sources on the internet
For example, data are available in the form of statistics on
economic and demographic activity from statistical data banks
Abstracts from newspapers, magazines, and other periodicals
from bibliographic data banks

12. Database Management System
DBMS is the software that permits an organization to
centralize data, manage them efficiently, and provide access to
the stored data by application programs .
DBMS acts as an interface between the application program
and the physical data files
DBMS has three components
 A data definition language
 A data manipulation language
 A data dictionary

13. Data Definition Language
The data definition language is the formal language used by
the programmers to specify the content and structure of
database
It defines each data element as it appears in the database before
that data element is translated into the forms required by
application programs

14. Data Manipulation Language
This language contains commands that permits end users and
programmers to extract data from the database to satisfy
information requests and develop applications
The most prominent data manipulation language today is
structured query language (SQL)

15. Data Dictionary
This is an automated or manual file that stores definitions of
data elements and data characteristics such as usage, physical
representation, ownership, authorization and security
Many data dictionaries can produce lists and reports of data
utilization, groupings, program location and so on

16. Functions of DBMS
Organizes data
Integrates data
Separates data
Controls data
Retrieves data
Protects data

17. Benefits of DBMS
Reduced programming costs
Reduced development and implementation time
Reduced program and file maintenance costs
Reduced data Redundancy
Increase flexibility

18. Data Storage and Retrieval
Data is not stored in a random fashion. It is organized for
efficient retrieval.
Sequential organization
Indexed Sequential Organization
Inverted List Organization
Direct Access Organization

19. Sequential Organization
It simply means storing and sorting in physical, contiguous
blocks within files on tape or disk
Records are also in sequence within each block
It is best suited in reading one record after another without a
search delay
The records can be added only at the end of the file

20. Indexed Sequential Organization
Data is stored in physically contiguous blocks and uses indexes
to locate records
Indexed Sequential Organization reduces the magnitude of the
sequential search and provides quick access for sequential and
direct processing
The drawback is the extra storage space required for the index.
It also takes long to search the index for data access or retrieval

21. Inverted List Organization
It differ from the previous in the index level and record storage
The indexed sequential method has a multiple index for a
given key, whereas the inverted list method has a single index
for each key type
In inverted list records are not needed to be stored in a
particular sequence. They are placed in data storage area but
indexes are updated for the record keys and location
Inverted lists are best for applications that request specific data
on multiple keys

22. Direct Access Organization
In direct access file organization, records are placed randomly
throughout the file
New records are added at the end of the file or inserted in
specific locations based on software commands
Records are accessed by addresses that specify their disk
locations. An address is required for locating a record, for
linking records , or for establishing relationships

23. Hierarchical Data Model
Employee
Compensation
Performance
Salary hist
Job assignments
Pension
Benefits
Life insurance
Health

24. Network Data Model
Course 1
Student 1
Student 2
Course 2
Student 3
Course 3
Student 4
Student 5
Student 6

25. Relational Data Model
Dept .no
Dep. A
Dep. B
Dep. C
D
D Emp
name loc
no
Emp E
E
E Dep.
. no name title sal no
E1
E2
E3
DA
DA
DB
E4
E5
DB
DC
E6
DA

26. Data Schemes
The schemes (schema) define categories of data and their
properties .
External Schema or user schema is the user’s view of a part
of the database
Conceptual Schema is the overall logical view of the database
Internal Schema or data storage definition is the way the data
is physically organized in storage

27. General Model
External Schemas
User View
Conceptual
Schema
User View
Internal
Schema
User View
Stored
Database

28. External Schema
Each user of the database (an application program or a person
formulating a query ) is concerned with only a small portion of
the database
Each user is interested in only a part of the entities in the
database, only part of the attributes of those entities, and
certain relationships among the entities
External schema consists basically of definitions of each of the
various external record types in the external view
The external schema is written using the DDL portion of the
user’s data sub language

29. Conceptual Schema
The conceptual schema is the logical view of the entire
database . It represents as closely as possible the real entities
and their relationships .
It contains integrity rules and authorization rules, but it does
not contain information about how the data items are stored

30. Internal Schema
The internal schema or physical data model describes how the
database is organized for physical storage and access
The internal schema includes information on ordering of
records, block sizes, storage indexes, use of pointers and access
strategies being used

31. Mapping
A mapping is a transaction of one schema to another
In order for a user to access data, the user view of the data as
reflected in the external schema must be translated into the
overall conceptual schema
In the same way, the conceptual/internal mapping translates
logical descriptions of data in the conceptual schema to
physical locations and access paths in the internal scheme

32. Mapping between Schemas view
External view
External
External schema1
External schema 2
Overall conceptual
view
Conceptual schema
Internal schema
(DDL)
Stored Database
External view
External schema 3