Overview of Data Base Systems Concepts and Architecture

Data Base Management System
Unit - 1
Overview of Data Systems Concepts and
Architecture
Date:
Presented By:
Rubal Sagwal
Department of Computer Engineering
2Rubal

Contents
• Introduction of Database
• DBMS
• Characteristics of database approach
• Advantages of DBMS
• Data models
• Schemas, Three schema architecture:
• The external level
• The conceptual level and
• The internal level.
• Data Independence
• Database languages and Interfaces
• Roles of Database Administrator
3

Introduction
Data – Data Hierarchy – Database – Database Proporites
4

Data
• What is Data?
• By data – we mean known facts that can be recorded
and that have implicit meaning.
• For example, consider the names, telephone numbers,
and addresses of the people you know.
• Google Says – “Facts, Figures, Statistics, particulars,
details”.
• https://youtu.be/djEZeF4KTaM
5

Contd…
Data
Data is collection of raw facts and figures.
Or
Facts and statistics collected together for reference or
analysis.
• Data is usually formatted in a specific way and can exist
in a variety of forms, such as numbers, text, etc.
6

Data Hierarchy
7
Database
File
Record
Field
Byte
Bit

Data Hierarchy
9
1. Bit: All data is stored in a computer's memory or storage devices in
the form of binary digits or bits. A bit can be either 'ON' of
'OFF' representing 1 or 0.
2. Byte: s a group of 8 bits. One byte can represent one character or, in
different contexts, other data such as a sound, part of a picture etc.
3. Field: is a group of characters. e.g. data held about a person may be
split into many fields including ID Number, Surname, Initials, Title,
Street, Town, etc.
4. Record: is a group of fields holding all the information about one
person or item.
5. File: a collection of records. A stock file will contain a record for each
item of stock, and so on.
6. Databse: may consist of many different files, linked in such a way
that information can be retrieved from several files at once.

Database
• A database is a collection of related data.
• We may consider the collection of words that make
up this slide of text to be related data and hence to
create a database.
10

Database Properties
• A database represents some aspect of the real
world, sometimes called the miniworld or the
universe of discourse (UoD).
• Changes to the miniworld are reflected in the
database.
• A database is a logically collection of data with
some inherent meaning.
• A random group of data cannot correctly be referred to
as a database.
11

Contd…
Database Properties
• A database is designed, built, and populated with
data for a specific purpose. It has an intended
group of users and some defined applications in
which these users are interested.
12

Database
• In other words – a database has some source from
which data is derived, some degree of interaction
with events in the real world, and an audience that
is actively interested in its contents.
• A database can be of any size.
• A database may be generated and maintained
manually or it may be computerized.
13

Database Example
• For example, the list of name, phone number, and
address represents hundred number of records.
• An example of a large commercial database is
Amazon.com. It contains data for over 20 million
books, CDs, videos, DVDs, games, electronics,
apparel, and other items. The database occupies
over 2 terabytes (a terabyte is 1012 bytes worth of
storage) and is stored on 200 different computers
(called servers).About 15 million visitors access
Amazon.com each day and use the database to
make purchases.
14

Why do we need Database
• To manage large chunks of data: Yes, you can store
data into a spreadsheet, but if you add large chunks of
data into the sheet, it will simply not work. For
instance: if your size of data increases into thousands of
records, it will simply create a problem of speed.
• Accuracy: When doing data entry files in a spreadsheet,
it becomes difficult to manage the accuracy as there
are no validations present in it.
• Ease of updating data: With the database, you can
flexibly update the data according to your convenience.
Moreover, multiple people can also edit data at same
time.
15

Why do we need Database
• Security of data: There is no denying the fact that
your data is less secure in spreadsheets. Anyone
can easily get access to file and can make changes
to it. With databases you have security groups and
privileges you set to restrict access.
• Data integrity: Data integrity also becomes a
question when storing data in spreadsheets. In
databases, you can be assured of accuracy and
consistency of data due to the built in integrity
checks and access controls.
16

DBMS
Data Base Management System – Functions of DBMS
17

Database Management System (DBMS)
• A database management system (DBMS) is a
collection of programs that enables users to create
and maintain a database.
• The DBMS is a general-purpose software system
that facilitates the processes of defining,
constructing, manipulating, and sharing databases
among various users and applications.
18

Functions of Database Management System
1. Defining a database involves specifying the data
types, structures, and constraints of the data to be
stored in the database.
2. Constructing the database is the process of storing
the data on some storage medium that is controlled
by the DBMS.
3. Manipulating a database includes functions such as
querying the database to retrieve specific data,
updating the database to reflect changes in the
miniworld, and generating reports from the data.
4. Sharing a database allows multiple users and
programs to access the database simultaneously.
19

• An application program accesses the database by
sending queries or requests for data to the DBMS.
• A query typically causes some data to be retrieved.
• A transaction may cause some data to be read and
some data to be written into the database.
20

Why do we need DBMS
22
• A database management system (DBMS) is a
collection of programs that manages the database
structure and controls access to the data stored in
the database.
• Improved data sharing.
• Integrity can be enforced
• Minimized data inconsistency.
• Providing Backup and Recovery
• Improved data security.

What are characteristics of Database
Approaches
23
• Manages Information: A system may have to
maintain information of various employees working
in its organization, their names, addresses, and
other details which may in later instance be
modified or deleted.
• Easy to operate on data: Inserting more data,
deleting un-useful data, updating, searching etc is
easy.

Contd…
What are characteristics of Database Approaches
24
• Self-Describing Nature of a Database System: A
fundamental characteristic of the database
approach is that the database system contains not
only the database itself but also a complete
definition or description of the database structure
and constraints.

Contd…
25
• Consistent: suppose you are initiating a transaction
wherein you have to transfer Rs 50 from Account A to
B. Say account A contains Rs 300 and B contains Rs 200.
You will execute the transaction in 2 steps. 1st subtract
rs 50 from A and 2nd Add 50 to B. Now the database
will reflect updated values A= 250 and B=250
• Now imagine ,there occurs a system failure after 1st
step of transaction. the database will reflect A=250 and
B=200. that means rs 50 is destroyed by the system.
This inconsistency is prevented by database approach.
Either all changes are reflected (ie. A=250 and B=250)
or none are (ie. A=300 and B=200).

Contd…
26
• Persistent: Once your transaction has completed
successfully ( we say the transaction is committed),
data will remain persistent, i.e. it will not be lost or
deleted until you do it manually.
• Security of Data: Only authorized users are allowed to
access the data.
• Supports multiple views: Different users may have
interest in different groups of data. User is allowed to
view the data in which he is interested.
EG. one user is only interested for student mark
list,other user is interested for courses attended by that
student, these multi-user views are satisfied by DBMS

Advantages of DBMS
28
1. Controlling Redundancy
2. Restricting Unauthorized Access
3. Providing Storage Structures and Search
Techniques for Efficient Query Processing
4. Providing Backup and Recovery
5. Providing Multiple User Interfaces
6. Enforcing Integrity Constraints
7. Flexibility
8. Availability of Up-to-Date Information

29
• Redundancy in storing the same data - that leads to
several problems.
• In traditional software development utilizing file processing,
every user group maintains its own files for handling its data-
processing applications. For example, consider the
UNIVERSITY database example, Teacher used to maintain
their own record, admin used to maintain their own record
and exam section used to maintain their own record.
• Duplication of effort: there is the need to perform a
single logical update—such as entering data on a new
student—multiple times: once for each file where
student data is recorded.

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• Storage space – is wasted when the same data is
stored repeatedly, and this problem may be serious for
large databases.
• Inconsistency – files that represent the same data may
become inconsistent. This may happen because an
update is applied to some of the files but not to others.
• In the DBMS approach, the views of different user
groups are integrated during database design. Ideally,
we should have a database design that stores each
logical data item in only one place in the database.

2. Restricting Unauthorized Access
31
• When multiple users share a large database, it is
likely that most users will not be authorized to
access all information in the database.
• For example, financial data is often considered
confidential, and only authorized persons are
allowed to access such data.

3. Providing Storage Structures and Search
Techniques for Efficient Query Processing
32
• Database systems must provide capabilities for
efficiently executing queries and updates
• Provide Index view.

4. Providing Backup and Recovery
33
• A DBMS must provide facilities for recovering from
hardware or software failures.
• The backup and recovery subsystem of the DBMS is
responsible for recovery.
• For example, if the computer system fails in the
middle of a complex update transaction, the
recovery subsystem is responsible for making sure
that the database is restored to the state it was in
before the transaction started executing

5. Providing Multiple User Interfaces
34
• Many types of users with varying levels of technical
knowledge use a database, a DBMS should provide
a variety of user interfaces.
• These include query languages for casual users,
programming language interfaces for application
programmers, etc.

6. Enforcing Integrity Constraints
35
• .The simplest type of integrity constraint involves
specifying a data type for each data item. For
example, if we specified that the value of the Class
data item within each STUDENT record must be a
one digit integer and that the value of Name must
be a string of no more than 30 alphabetic
characters.
• So no Class field will store the value more than
one digit and no Name would store the name more
30 character.

7. Flexibitlity
36
• It may be necessary to change the structure of a
database as requirements change.
• For example, a new group of user may need some
information that is not currently in the database.
• In response, it may be necessary to add a file to the
database or to extend the data elements in an
existing file.
• It is easy to add, delete or modify the databse.

8. Availability of Up-to-Date Information
37
• A DBMS makes the database available to all users.
As soon as one user’s update is applied to the
database, all other users can immediately see this
update.

Actors on the Scene and
Workers Behind the
Scene
38

Actors on the Scene – Introduction
39
• For a small personal database, such as maintaining
the class record, one person typically defines,
constructs, and manipulates the database, and
there is no sharing.
• However, in large organizations, many people are
involved in the design, use, and maintenance of a
large database with hundreds of users
• Here we identify the people whose jobs involve the
day-to-day use of a large database; we call them
the actors on the scene.

Actors behind the scene
40
• Those who work to maintain the database system
environment but who are not actively interested in
the database contents as part of their daily job.

Actors – on and behind the scene
41
Actors
On the Scene
Database
Administration
Database
Designers
End users
Casual End Users
Naïve or
Parametric Users
Sophisticated
End Users
Standalone
Users
Behind the
Scene
DBMS System
Designers and
implementers
Tool Developers
Operators and
maintainance
personal

Actors on the Scene
42
1. Database Administrator (DBA): The DBA is responsible
for authorizing access to the database, coordinating and
monitoring its use, and acquiring software and
hardware resources as needed. The DBA is accountable
for problems such as security breaches and poor system
response time.
2. Database Designers: Database designers are responsible
for identifying the data to be stored in the database and
for choosing appropriate structures to represent and
store this data, It is the responsibility of database
designers to communicate with all prospective database
users in order to understand their requirements and to
create a design that meets these requirements .Database
designers typically interact with each potential group of
users and develop views of the database that meet the
data and processing requirements of these groups.

Actors on the Scene
43
3. End Users: are the people whose jobs require
access to the database for querying, updating, and
generating reports; the database primarily exists for
their use. There are several categories of end users:
a. Casual End Users: occasionally access the database,
but they may need different information each time.
They use a sophisticated database query language to
specify their requests and are typically middle- or
high-level managers or other occasional browsers.

Actors on the Scene – End Users
44
b. Naïve Users: Their main job function revolves
around constantly querying and updating the
database, using standard types of queries and
updates The tasks that such users perform are
varied:
• Bank tellers check account balances and post
withdrawals and deposits.
• Reservation agents for airlines, hotels, and car rental
companies check availability for a given request and
make reservations.

Actors on the Scene – End Users
45
c. Sophisticated end users: include engineers,
scientists, business analysts, and others who
thoroughly familiarize themselves with the facilities
of the DBMS in order to implement their own
applications to meet their complex requirements.
d. Standalone users: maintain personal databases
by using ready-made program packages that
provide easy-to-use menu-based or graphics-based
interfaces. An example is the user of a tax package
that stores a variety of personal financial data for tax
purposes.

Actors on the Scene
46
4. System Analysts and Application Programmers
(Software Engineers: System analysts determine the
requirements of end users, especially naive end
users, and develop specifications for standard
canned transactions that meet these requirements.
Application programmers implement these
specifications as programs; then they test, debug,
document, and maintain these canned transactions.

Workers Behind the Scene
47
These persons are typically not interested in the
database content itself.
1. DBMS system designers and implementers: design and
implement the DBMS modules and interfaces as a
software package.
2. Tool developers: design and implement tools—the
software packages that facilitate database modeling and
design, database system design, and improved
performance. Tools are optional packages that are often
purchased separately.
3. Operators and maintenance personnel (system
administration personnel): are responsible for the actual
running and maintenance of the hardware and software
environment for the database system.

Data Models
48
• A data model—a collection of concepts that can be
used to describe the structure of a database—
provides the necessary means to achieve this
abstraction.
• By structure of a database we mean the data
types, relationships, and constraints that apply to
the data.
• Data abstraction – refers to the suppression or
hiding of details of data organization and storage,
and the highlighting of the essential features for
an improved understanding of data.

Categories of Data Models
49
1. High-level or conceptual data models – provide
concepts that are close to the way many users
identify data. Conceptual data models use
concepts such as entities, attributes, and
relationships.
2. Low-level or physical data models – provide
concepts that describe the details of how data is
stored on the computer storage media.

Categories of Data Models
50
3. Representational (or implementation) Data
Models:
a. Relational Data Model
b. Network Data Model
c. Hierarchical Data Model

Schemas, Instances, and
Database State
51

Schemas
52
• Data Base Schema: The description of a database
is called the database schema, which is specified
during database design and is not expected to
change frequently.
• Most data models have certain conventions for
displaying schemas as diagrams. A displayed
schema is called a schema diagram.

Instance
53
• A database instance is a set of memory structures
that manage database files.
• A database is a set of physical files on disk created
by the CREATE DATABASE statement.
• The instance manages its associated data and
serves the users of the database.

Schemas and Instance
54
• This diagram displays the structure of each record
type but not the actual instances of records. We
call each object in the schema—such as STUDENT
or COURSE—a schema construct.

Schemas Diagram
55
• A schema diagram displays only some aspects of a
schema, such as the names of record types and
data items, and some types of constraints.
• Other aspects are not specified in the schema
diagram; for example, above figure shows neither
the data type of each data item, nor the
relationships among the various files.
• Many types of constraints are not represented in
schema diagrams.

Data Base State or Snapshot
56
• The data in the database at a particular moment in
time is called a database state or snapshot.
• It is also called the current set of occurrences or
instances in the database.
• In a given database state, each schema construct has its
own current set of instances; for example, the
STUDENT construct will contain the set of individual
student entities (records) as its instances.
• Every time we insert or delete a record or change the
value of a data item in a record, we change one state
of the database into another state.

Database Schema and Database State
57
• The distinction between database schema and
database state is very important.
• When we define a new database, we specify its
database schema only to the DBMS.
• At this point, the corresponding database state is the
empty state with no data.
• We get the initial state of the database when the
database is first populated or loaded with the initial
data.
• From then on, every time an update operation is
applied to the database, we get another database
state.
• At any point in time, the database has a current state.

The Three-Schema
Architecture
58

The Three-Schema Architecture
59

60
• Three Schema Architecture is to separate the user
applications from the physical database. In this
architecture, schemas can be defined at the
following three levels:
1. The internal level – has an internal schema,
which describes the physical storage structure of
the database. The internal schema uses a
physical data model and describes the complete
details of data storage and access paths for the
database.

61
2. The conceptual level – has a conceptual schema,
which describes the structure of the whole
database for a community of users.
• The conceptual schema hides the details of
physical storage structures and concentrates on
describing entities, data types, relationships, user
operations, and constraints.

62
3. The external or view level – includes a number of
external schemas or user views.
• Each external schema describes the part of the
database that a particular user group is interested
in and hides the rest of the database from that
user group.
• As in the previous level, each external schema is
typically implemented using a representational
data model, possibly based on an external schema
design in a high-level data model.

The Three-Schema Architecture – mapping
63
• Notice that the three schemas are only descriptions of data; the stored
data that actually exists is at the physical level only.
• In a DBMS based on the three-schema architecture, each user group
refers to its own external schema.
• Hence, the DBMS must transform a request specified on an external
schema into a request against the conceptual schema, and then into a
request on the internal schema for processing over the stored database.
• If the request is a database retrieval, the data extracted from the stored
database must be reformatted to match the user’s external view.
• The processes of transforming requests and results between levels are
called mappings. These mappings may be time-consuming, so some
DBMSs—especially those that are meant to support small databases—
do not support external views. Even in such systems, however, a certain
amount of mapping is necessary to transform requests between the
conceptual and internal levels.

Data Independency
64
• Data independence – which can be defined as the
capacity to change the schema at one level of a
database system without having to change the
schema at the next higher level. We can define
two types of data independence:
1. Logical data independency
2. Physical data independency

Data Independency
65
1. Logical data independence – is the capacity to
change the conceptual schema without having to
change external schemas or application programs.
• We may change the conceptual schema to expand
the database (by adding a record type or data
item), to change constraints, or to reduce the
database (by removing a record type or data item).
• Changes to constraints can be applied to the
conceptual schema without affecting the external
schemas or application programs.

Data Independency
66
2. Physical data independence – is the capacity to
change the internal schema without having to change
the conceptual schema.
• Hence, the external schemas need not be changed as
well.
• Changes to the internal schema may be needed
because some physical files were reorganized—for
example, by creating additional access structures—to
improve the performance of retrieval or update. If the
same data as before remains in the database, we
should not have to change the conceptual schema.

Data Independency
67
• Generally, physical data independence exists in
most databases and file environments where
physical details such as the exact location of data
on disk, and hardware details of storage encoding,
placement, compression, splitting, merging of
records, and so on are hidden from the user.
Applications remain unaware of these details.
• On the other hand, logical data independence is
harder to achieve because it allows structural and
constraint changes without affecting application
programs—a much stricter requirement.

Database Languages
Rubal_CN 68

Database Langauges
69
1. Data definition language (DDL): is used by the
DBA (Database Administrator) and by database
designers to define both schemas. The DBMS will
have a DDL compiler whose function is to process
DDL statements in order to identify descriptions of
the schema constructs and to store the schema
description in the DBMS catalog.
• The DDL is used to specify the conceptual schema only.

Database Languages
70
2. Storage definition language (SDL): is used to specify
the internal schema.
3. View definition language (VDL): to specify user views
and their mappings to the conceptual schema, but in
most DBMSs the DDL is used to define both conceptual
and external schemas.
4. Data manipulation language (DML): Once the
database schemas are compiled and the database is
populated with data, users must have some means to
manipulate the database. Typical manipulations include
retrieval, insertion, deletion, and modification of the
data. The DBMS provides a language called the data
manipulation language (DML) for these purposes.

DBMS Interface
Menu-based Interface – Forms-based Interface – GUI –
Natural Language Interface – Speech Input and Output
Interface – interface for Parametric Users – Interfaces for the
DBA
Rubal_CN 71

DBMS Interface
72
1. Menu-Based Interfaces for Web Clients or
Browsing: These interfaces present the user with
lists of options (called menus) that lead the user
through the formulation of a request.
• In this the query is composed step-by-step by picking
options from a menu that is displayed by the system.
• Pull-down menus are a very popular technique in Web-
based user interfaces.
• They are also often used in browsing interfaces, which
allow a user to look through the contents of a database
in an exploratory and unstructured manner.

DBMS Interface
73
2. Forms-Based Interfaces: A forms-based interface
displays a form to each user. Users can fill out all of
the form entries to insert new data, or they can fill
out only certain entries, in which case the DBMS will
retrieve matching data for the remaining entries.
3. Graphical User Interfaces: A GUI typically displays
a schema to the user in diagrammatic form. The
user then can specify a query by manipulating the
diagram. In many cases, GUIs utilize both menus and
forms. Most GUIs use a pointing device, such as a
mouse, to select certain parts of the displayed
schema diagram.

DBMS Interface
74
4. Natural Language Interfaces: These interfaces accept requests written
in English or some other language and attempt to understand them. A
natural language interface usually has its own schema, which is similar to
the database conceptual schema, as well as a dictionary of important
words. The natural language interface refers to the words in its schema, as
well as to the set of standard words in its dictionary, to interpret the
request. If the interpretation is successful, the interface generates a high-
level query corresponding to the natural language request and submits it
to the DBMS for processing; otherwise, a dialogue is started with the user
to clarify the request.
Today, we see search engines that accept strings of natural language (like
English) words and match them with documents at specific sites (for local
search engines) or Web pages on the Web at large (for engines like
Google or Ask).They use predefined indexes on words and use ranking
functions to retrieve and present resulting documents in a decreasing
degree of match. Such “free form” textual query interfaces are not yet
common in structured relational or legacy model databases, although a
research area called keyword-based querying has emerged recently for
relational databases.

DBMS Interface
75
5. Speech Input and Output: Applications with
limited vocabularies such as inquiries for telephone
directory, flight arrival/departure, and credit card
account information are allowing speech for input
and output to enable customers to access this
information. The speech input is detected using a
library of predefined words and used to set up the
parameters that are supplied to the queries. For
output, a similar conversion from text or numbers
into speech takes place.

DBMS Interface
76
6. Interfaces for Parametric Users: Parametric users
– such as bank teller (cashiers/ clerk etc), often have
a small set of operations that they must perform
repeatedly. For example, a teller is able to use single
function keys to invoke routine and repetitive
transactions such as account deposits or
withdrawals, or balance inquiries. Systems analysts
and programmers design and implement a special
interface for each known class of naive users.
Usually a small set of abbreviated commands is
included, with the goal of minimizing the number of
keystrokes required for each request.

DBMS Interface
77
7. Interfaces for the DBA: Most database systems
contain privileged commands that can be used only
by the DBA staff. These include commands for
creating accounts, setting system parameters,
granting account authorization, changing a schema,
and reorganizing the storage structures of a
database.

Roles of Database
Administrator
Deciding the hardware device – Software installation and
Maintenance - Data Extraction, Transformation, and Loading -
Managing Data Integrity – Database Design – Database
implementation – Security - Database Backup and Recovery –
Authentication - Performance Monitoring
Rubal_CN 78

Roles of Database Administrator
79
There are lots of role and duties of a database
administrator (DBA). He is responsible for managing,
securing and taking care of the database system.
1. Deciding the hardware device: Depending upon
the cost, performance and efficiency of the
hardware, it is DBA who have the duty of deciding
which hardware devise will suit the company
requirement. It is hardware that is an interface
between end users and database so it needed to be
of best quality.

80
2. Software installation and Maintenance:
• A DBA often collaborates on the initial installation and
configuration of a new Oracle, SQL Server etc
database. The system administrator sets up hardware
and deploys the operating system for the database
server, then the DBA installs the database software
and configures it for use. As updates and patches are
required, the DBA handles this on-going maintenance.
• And if a new server is needed, the DBA handles the
transfer of data from the existing system to the new
platform.

81
3. Data Extraction, Transformation, and Loading
• Known as ETL, data extraction, transformation, and
loading refers to efficiently importing large
volumes of data that have been extracted from
multiple systems into a data warehouse
environment.
• This external data is cleaned up and transformed
to fit the desired format so that it can be imported
into a central repository.

82
4. Managing Data Integrity:
• Data integrity should be managed accurately
because it protects the data from unauthorized
use. DBA manages relationship between the data to
maintain data consistency.
5. Database design:
• The logical design of the database is designed by
the DBA. Also a DBA is responsible for physical
design, external model design, and integrity
control.

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6. Database implementation:
• Database has to be implemented before anyone
can start using it. So DBA implements the database
system. DBA has to supervise the database loading
at the time of its implementation.
7. Security:
• A DBA needs to know potential weaknesses of the
database software and the company’s overall
system and work to minimize risks. No system is
one hundred per cent immune to attacks, but
implementing best practices can minimize risks.

84
8. Database Backup and Recovery
• DBAs create backup and recovery plans and procedures
based on industry best practices, then make sure that
the necessary steps are followed. Backups cost time
and money, so the DBA may have to persuade
management to take necessary precautions to preserve
data.
• System admins or other personnel may actually create
the backups, but it is the DBA’s responsibility to make
sure that everything is done on schedule.
• In the case of a server failure or other form of data
loss, the DBA will use existing backups to restore lost
information to the system.

85
9. Authentication
• Setting up employee access is an important aspect of database
security. DBAs control who has access and what type of access
they are allowed. For instance, a user may have permission to
see only certain pieces of information, or they may be denied the
ability to make changes to the system.
10. Performance Monitoring
• Monitoring databases for performance issues is part of the on-
going system maintenance a DBA performs. If some part of the
system is slowing down processing, the DBA may need to make
configuration changes to the software or add additional
hardware capacity. Many types of monitoring tools are available,
and part of the DBA’s job is to understand what they need to
track to improve the system.

Summery
Rubal_CN 86
• Have Studied Terminology of DBMS:
• Data
• Data Hierarchy
• Data Base
• DBMS
• Data Base Management Systems
• Need
• Advantages
• Actors on the and behind the scene
• Overview of Data Models
• Schemas, Instances and Database state
• Three Level Architecture
• Database languages
• Roles of DBA

Overview of Data Base Systems Concepts and Architecture

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