Traditional approach to information processing
Disadvantages of traditional approach
Database Approach to Information Processing
Logical versus PhysicalViews Of Data Storage
3. DBMS Users
Advantages of DBMS
What is a Database?
Elements of DBMS
How does a DBMS work?
Data Base Models
4. Information is a key word in modern management.
Having a large quantity of information on hand does
not guarantee ready access to any particular piece
Perhaps the most important challenge facing
information systems is to provide users with timely
and versatile access to data stored in computer files.
5. In a dynamic business environment there are many
unanticipated needs for information.
The basic underlying data to satisfy the information
needs are contained in computer files but cannot be
accessed and output in a suitable format on a timely
For effective decision-making, one should have access
to information whenever needed, and it should be up
to date and cost effective
6. A Data Base Management System is an
effective data management tool, provides
invaluable help in coping with data organization
and access problems, and improves the quality
of information available to the management for
7. The traditional approach to information
processing is file-oriented.
Prior to the advent of data base management
systems(DBMS), each application maintained its
own master file and generally had its own set of
Files are custom-designed for each application,
and generally there is little sharing of data
among the various applications.
8. Programs are dependent on the files and vice-
versa; that is, when the physical format of file is
changed, the program also has to be changed.
The traditional approach is file oriented because
the primary purpose of many applications is to
maintain on the master file the data required to
produce management information.
9. Therefore, the file is the centre-piece of each
Although the traditional, file oriented approach
to information processing is still widely used, it
does have some disadvantages.
11. Payroll file
Pay Rate Year-to-Date-
Age Date Hired occupation
12. A DBMS is a set of programs that serve as an
interface between application programs and a
set of coordinated physical files called a
A DBMS provides the capabilities for creating,
maintaining, and changing a data base.
A data base is a collection of data.
The physical files of the data base are analogous
to the master files of the application files.
14. The data base management system stores,
updates, and retrieves data for all application
Data can be readily shared among these
programs to prevent data redundancy Easy-to-
use query languages allow users to produce ad-
15. Physical view : Similar to traditional file
systems. It deals with the actual location of bits
and bytes on memory devices.
Logical view : Represents data in a format that
is meaningful to the user and the application
programmer.The emphasis here is on
interrelating data fields and records such that
they represent the underlying business reality.
17. Data base is the physical collection of data.
The data must be stored on direct-access
devices like magnetic disks.
Well managed installations create backup
copies of the data base on offline storage media
such as magnetic tapes.
18. The hardware, then consists of the secondary
storage volumes such as disks, drums, tapes,
etc., on which the data base resides together
with the associated devices, control units,
channels, and so forth.
The security measures are extremely important
in a data base environment, since departments
and application programs may be dependent on
a single, centralized data base.
19. The users of database system can be classified
depending on their degree of expertise or the mode
of their interactions with the DBMS.
Three classes of users are application programmer,
end-user or traditional users(such as management),
and database administrator.
Users interact with the DBMS indirectly via
application programs or directly via simple query
20. The user’s interactions with the DBMS also
include the definition of the logical relationships
in the database(the logical view), and the input,
alteration, deletion, and manipulation of data.
21. Centralized management and control of data.
The Database administrator is the focus of the
Any application requiring a change in the structure
of a data record requires an arrangement with the
DBA, who makes the necessary modifications.
Such modifications do not affect other applications
or users of the record in question.
22. 1. Reduction of Redundancies
2. Sharing Data
5. Conflict Resolution
6. Data Independence
23. A database is an organized collection of
A DBMS allows you to enter, store, manipulate,
and retrieves information organized into
A DBMS provides interactive access to your
data bases and provides an easy way to create
24. When a body of information becomes too large or
the retrieval demands on it become too complex to
manage manually, the information system should
Every computer application has unique
Database management systems are general-
purpose programs that dramatically reduce the
time necessary to computerize an application.
25. The purpose of a DBMS is to provide two main
A mechanism for organizing, structuring and storing
A mechanism for accessing data that provides a
measure of data independence, i.e., to some extent it
insulates application programs from changes to the
26. Data base management system is a complex
software package that enables the user to
communicate with the data base.
The DBMS interprets user commands so that the
computer system can perform the task required.
The work of the system designer and the
application programmer, the DBMS as viewed by
its user, will normally consist of three main areas:
27. 1. The data definition facility or data definition
2. The data manipulation facility or data
3. Utilities and Ancillary Software.
28. This is the means by which the content and
format of data to be stored is described and the
structure of the data base is defined, including
relationships between records and indexing
This definition of the data base is often known
29. DDL is essentially the link between the logical
and physical views of the data base.
Logical refers to the way the user views data.
Physical refers to the way the data are physically
30. The logical structure of a data base is sometimes called a
A subschema is the way a particular application views the
data from the data base.
There may be many users and application programs
utilizing the same data base, and, therefore, many
different sub schemas can exist.
Each user or application program uses a set of DDL
statements to construct a subschema which includes only
those data elements which are of interest.
32. DDL is used to define the physical characteristics of
each record: the fields within the record, and each
field's logical name, data type, and length.
The logical name (such as SNAME for the student
name field), is used by both application programs
and users to refer to a field for the purpose of
retrieving or updating the data in it.
DDL is also used to specify relationships among the
33. 1. Describe the schema and subschema's.
2. Describe the fields in each record and the record's logical
3. Describe the data type and name of each field.
4. Indicate the keys on the record.
5. Provide for data security restrictions.
6. Provide for logical and physical data independence.
7. Provide means of associating related data.
34. This is a powerful set of procedural commands that
allow the programmer to easily store, retrieve and
alter data on the data base using the most
appropriate access strategies.
DML provides the techniques for processing the
data base, such as retrieval, sorting, display, and
deletion of data or records.
DML should include a variety of manipulation verbs
and operands for each verb.
36. Most data manipulation languages interface with high-
level programming languages such as COBOL or PL/I.
These languages enable a programmer to perform unique
data processing that the DBMS's data manipulation
language cannot perform.
A key feature of a DML is that it uses logical names (such
as SNO for student number) instead of physical storage
locations when referring to data.
The capability is Possible since the data definition
provides the linkage between the logical view of data and
their physical storage.
37. Provide the techniques for data manipulation such as
deletion, replacement, retrieval, sorting or insertion of
data or records.
Enable the user and application programs to process
data by using logically meaningful data names rather
than physical storage locations.
38. Provide interfaces with programming languages. A
DML should support several high-level languages
such as COBOL, PL/I, and FORTRAN.
Allow the user and application programs to be
independent of physical data storage and data
Provide for the use of logical relationships among
39. DBMS are normally provided a range of
products that fall into three main categories:
1. Those that aid the physical administration of
the data base such as dumping, logging,
recovery, re -organization, data base
initialization and fast initial load utilities.
40. 2. Those that help the data base administrator
and systems designer to coordinate and keep
track of the data on the data base, such as data
3. Those that help to reduce the effort of system
development and implementation by providing
powerful generalized facilities such as Report
Generation and Query Packages.
41. DBMS has a compiler or translator program that
accepts source definitions of the data base and
produces a machine readable data definition
which is almost always stored on a disk library
43. Data manipulation facilities are provided by procedural
commands that are usually used in conjunction with a
conventional programming language such as COBOL or
PL/I known as the 'Host Language'.
The DBMS supplier then provides a pre-processor to
translate the DML commands into the Host Language so
that the whole program can then be compiled, using the
standard compiler or assembler.
The rest of the program logic for processing transaction
files and carrying out mathematical or logical functions is,
thus, written in the normal way.
45. 1.The load stage in which the data descriptions
are accessed and linked to the program
definitions.This allows data base changes
without having to re -compile programs.
2.The execute stage in which the DBMS
routines are accessed by 'CALL' statements
actually carry out the commands. Generalized
functions such as logging and privacy checking
are carried out by the DBMS, routines.
46. Data bases from the real world are frequently
described within the framework of data models.
Usually there are two classes of data models
associated with data base management system
software: one is referred to as the conceptual or
semantic data model and the other is called
physical data model.
The conceptual data model provides an
environment to the user for interacting with the
47. The user can formulate his queries pertinent to the
data base within the frame of the conceptual data
Thus, conceptual models are the basis for
development of high-level query languages.
The physical data model helps the data base
administrator (i.e., users authorized to change
physical data) to organize the data and store them
in the computer so that subsets of the relevant to
the user's request can be processed efficiently.
49. The relational model is based on the concepts of
relational theory and the hierarchical and network
models are based on the concepts of graph theory.
Each of these types of models has some
advantages over the others.
Some real -world data base management systems
allow users to model and implement data on a tree,
network, or relational basis; others allow only one
model, such as relational.
50. The basic concepts of relational models were
introduced by Dr. E. F. Codd in the early nineteen
In the relational model, the data are viewed as a
collection of nonhierarchical time- varying
These are special constructs of mathematical
relations and are different from the traditional data
processing files and tables.
51. This view of the data enables the user to apply
the powerful operations and expressions of
relational algebra to data manipulations.
This model provides a means of describing data
with its natural structure only, that is, without
superimposing any additional structure for
machine representation purposes.
52. It provides a basis for a higher -level data language that
yields maximal independence between the machine
representation and organization of data.
It also provides a sound basis for treating derivability,
redundancy, and consistency of relations.
In this model, relational algebra has been used to
decompose a complex logical structure into a collection
of simple relations so that complex relations of the real
world can be expressed; also accessing and updating of
data can be made simple and efficient.
53. A relational data base is composed of one or more
relations. Each can be visualized as a table of data or file.
Each row (tuple) in the relation represents one entity
(such as a student in a student data base or an employee
in a personnel data base).
Each column (attribute) 'name' is drawn from the
domain of names in the data base.
The value of an attribute is called an item. In any relation
no two rows can be identical, and the ordering of the
rows should not be significant.
54. An attribute or set of attributes whose values
uniquely identify a row of a relation is called a key.
If a relation has more than one key, it -is preformed
to designate one of them as the primary key.
In relational data base systems you can enter data
without too much regard for how you are going to
use it; that is, you do not have to know how records
will be combined when you enter the data.
55. However, if you do not plan how you are going
to use data and enter it according to that plan,
you have to spend some time getting the
information out as the data base program
searches through your data base files, makes
the proper combinations, and records the
56. If you knew ahead of time how you wanted your
information served, you could have recorded it
accordingly in a single file and saved yourself a
lot of time when you retrieved it.
57. A company maintains an education and training
department whose function is to run various training
courses. Each course is offered at different locations
within the company.The details of education data base
is as follows:
1) For each course; Course number (unique), course title,
course description, details of prerequisite course, and
details of all offerings (past and planned).
2) For each prerequisite course; Course number and title.
58. 3) For each offering of a given course: Date,
location, format, details about teachers and
4) For each teacher of a given offering:
Employee number and name.
5) For each student of a given offering:
Employee number, name and grade.
60. In relational data base, one can combine records from different
files as long as the records in the different files have one field in
Under this system one can, theoretically, combine retrieve
selected records using a common field from an unlimited
number of files with command- as SELECT, PROJECT and
SELECT operation selects a record or set of record-
corresponding to the value of a field.
PROJECT creates subset records from existing records whereas
JOIN command combines records into new records.
61. Data is represented by a tree -structure type of organization.
The hierarchical tree specifies what record types are allowed
to be included in the data base and the permissible relations
between record types.
Any record other than the root of the tree must be connected
with a superior record (the parent).
Thus, to insert a record the user must select the parent record
When a record is deleted, all the descendants of the record
are also deleted.
62. The hierarchical data base is made up -of records,
as is the relational data base, except that the
records in a hierarchical data base do not have to
be broken up into fields.
The records can look like relational records with
several fields per record like a one-dimensional
array of data items.
In a hierarchical system, however, the connections
between files do not depend on the data in the
63. The connections are defined at the start and are
fixed for the life of the data base.
In this system, fileA is always linked to file B, no
matter what the contents of these two files are.
And, naturally enough, the connection between
record types is hierarchical.
64. These connections are called the structure of
the data, and a diagram of them looks like an
Figure shows the data structure of the
hierarchical data base.
66. The file at the top is called the parent or owner
file, while the files at the bottom are called the
child or member tiles:The identifying
characteristic of this system is the one -to -many
connection between the owner and the member
In other words the member files have only one
67. To implement a hierarchical data base, the
designer must first specify how the records are
related to one another.
One common method of implementation is the
use of pointers to maintain the relationship
between tiles whose contents have similar
69. COURSE is a root segment type, the other
segments are dependent segment type.
Each dependent has a parent (segment type), e.g.,
the parent ofTEACHER is OFFERING.
Each parent has at least one child (segment type).
Retrieval of information from any segment type
requires specifying the hierarchical path from the
root to the required segment.
70. Network model is the generalization of the
In the network model, a segment can have multiple
In general, the segments are grouped as levels but
logical associations can exist between segments
belonging to any level.
Although the logical associations are directional in
nature, any two levels can have both types of
71. In general, many -to -many logical associations
can exist between any two segments and also
The diagrammatic representation of the
different logical associations between the
segments resembles in a graph.
72. In general, these logical associations between instances
are implemented by pointers the data set or by creating
connecting relations that reflect the many -to -many
associations bet the instances.
Most of the current interest in the network approach can
be traced back to the publication of the final report of
the CODASYL Data BaseTask Group (DBTG) in April 1971.
The report noted that one of the most important aspects
of the DBTG logical model is the set concept.
73. Each occurrence of a set, represents a hierarchical
relationship between the owner record in the set
and the corresponding members.
Connections are made by a chain of pointers that
start from the owner, pass through all the
members and finally return to the owner record.
Set types are also represented using the Bachman
'data structure diagram' technique.
75. In the diagram, the names on the arrows are set
names; each set has a type of record as its
owner; another record as its members.
In the set calledCOURPRE, the record COURSE
is the owner and the record PREREQ is the