2.
Problems with file processing systems
Inconsistent data
Inflexibility
Limited data sharing
Poor enforcement of standards
Excessive program maintenance
3.
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.
Levels of Data
4.
Controlled Redundancy
Ease of learning and use
Data independence
Accuracy and Integrity
Privacy and security
Shared
Recovery from failure
Performance
Objectives of Data Base
5.
Operational Data Base
Analytical Data Base
Data Warehouse Data Base
Distributed Data Base
End User Data Base
External Data Base
Types of Data Bases
6.
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
Operational Database
7.
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
Analytical Database
8.
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
Data Warehouse Databases
9.
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
Distributed Database
10.
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.
End User Database
11.
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
External Database
12.
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
Database Management System
13.
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
Data Definition Language
14.
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)
Data Manipulation Language
15.
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
Data Dictionary
16.
Organizes data
Integrates data
Separates data
Controls data
Retrieves data
Protects data
Functions of DBMS
17.
Reduced programming costs
Reduced development and implementation time
Reduced program and file maintenance costs
Reduced data Redundancy
Increase flexibility
Benefits of DBMS
18.
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
Data Storage and Retrieval
19.
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
Sequential Organization
20.
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
Indexed Sequential Organization
21.
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
Inverted List Organization
22.
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
Direct Access Organization
26.
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
Data Schemes
28.
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
External Schema
29.
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
Conceptual Schema
30.
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
Internal Schema
31.
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
Mapping
