Relational Database Management System(17332)

Prepared By

Ms. Harsha C. Kunwar

G.H. Raisoni Polytechnic, Nagpur

2015-16

CHAPTER -01DATABASE SYSTEM CONCEPT

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Lecture - 1 An Introduction to Database

DATA :- Data is anything in a form suitable for use with a computer.

Data is often distinguished from programs. A program is a Set of instructions that detail a task for the computer to perform.

In this sense, data is thus everything that is not program code

Database :- A database is a collection of information that is organized so that it can easily be accessed, managed, and updated.

DBMS :- In database management system (DBMS), data files are the files that store the database information, whereas other files, such as index files and data dictionaries, store administrative information, known

as metadata.

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Disadvantages of File Processing System

1. Program-Data Dependence

2. Duplication of Data.

3. Limited data sharing.

4. Lengthy Development Times.

5. Excessive Program Maintenance.

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List advantages of DBMS

1. Reduction in Redundancy: Duplication of records is reduced.

2. Avoiding Inconsistency: As the redundancy is reduced inconsistency is avoided.

3. Maintaining Integrity: Accuracy is maintained.

4. Sharing of data: Sharing of data is possible.

5. Enforcement of Security: Security can be enforced.

6. Transaction support.

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Lecture 02DBMS Vs. RDBMS

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Various DBMS And RDBMS Software

• RDBMS S/W:- db/2, mySQL, sql/server, Oracle

• DBMS S/W:-IBM’s IMS database, db/2, mySQL, sql/server, Oracle,FOXPRO

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Data AbstractionData Abstraction :- It is a process through the complicated details related to data that how it is stored & maintained is hidden from the user

Three levels of abstraction are as follows:

1) Physical level

2) Logical level

3) View level

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Contd.. 1) Physical Level:• It is lowest level of abstraction.• This level defines lowest complicated data structure of database system.• This level hidden from user.• It defines how the data are stored.

2) Logical Level:• The level next to physical level is called logical level.• This level defines what data stored in the database and what the relationships

among these data .• Fully decides the structure of the entire database.

3) View Level:• This level is used to show the part of database to user.• There is more complexity in physical as well as logical level so user should not

interact with complicated database.• So different view of database can be created for user to interact with database

easily.

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Lecture 03 Database Languages

There are three types of database languages

1. Data Definition Language (DDL) commands provide means for defining relation schema, deleting relations, creating indices, views and modifying relation schemas.

E.g. CREATE TABLE/VIEW/INDEX to create a table/view/index in the

database DROP TABLE to remove a table from the database ALTER TABLE to add, modify or remove columns from a table in the

database

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Contd..

2) Data Manipulation Language (DML) commands manipulates the data i.e. they perform the operations of insertion, deletion, updating and selection of data.

E.g. SELECT to select rows of data from a table INSERT to insert rows of data into a table UPDATE to change rows of data in a table DELETE to remove rows of data from a table RENAME to change the name of table

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Contd..3) Data Control Language(DCL):

• It is the component of SQL statement that control access to data and to database.• DCL commands are used to enforce database security in a multiple user

database• environment. Two types of DCL commands are GRANT and REVOKE, also

COMMIT,• ROLLBACK and SAVEPOINT used to provide the security. Only database

administrator’s• or owners of the database object can provide/remove privileges on a database

object.• E.g.

1. GRANT

2. REVOKE

3. COMMIT

4. ROLLBACK

5. SAVE POINT

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Lecture 04Instances & Schema

Instances :- The collection of information stored in the database at a particular moment is called as an instance.• The value of the variable declared in the program are corresponding to the

instance

Schema :- The overall design of the database is known as schema. The database schema are partitioned at different level of abstraction.• A database schema is related with the variable which are declared in the

program. Schema does not get changed frequently. The schema defined at different level are as follows

Physical Schema Logical Schema Sub Schema

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Data Independence

Data Independence :- The ability to modify a schema definition in one level without affecting a schema definition in next higher level is called data independence.

There are two types of data independence

1. Physical data independence

2.Logical data independence.

1. Physical data independence :- Physical data independence is the ability to change internal level without having change in conceptual or external level.

2. Logical data independence :- Logical data independence is the ability to change conceptual level without having change in external level or application program.

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Lecture 05Components of DBMS

Different components of DBMS are:

1. Query Processor (DDL interpreter, DML compiler, Embedded DML Pre-Compiler, Query Evaluation Engine)

DML Compiler : It translates DML statements of High level language into low level instructions that query evaluation engine understands.

Embedded DML Pre-Compiler: It converts DML statements embedded in application program to

normal procedural calls in host language. DDL Interpreter: It interprets DDL statements and records them in a set of

tables containing

metadata. Query Evaluation Engine: It executes low level instructions generated by

DML compiler and

DDL interpreter.BACK

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Contd..

2. Storage Manager (Authorization and Integrity Manager, Transaction Manager, File Manager, Buffer Manager)

Transaction Manager: It ensures that the database remains in consistent state despite the system failures and that concurrent transaction execution proceeds without conflicting.

File Manager: It manages the allocation of space on disk storage& data structures used to represent information stored on disk.

Buffer Manager: It is responsible for fetching data from disk storage into main memory and deciding what data to cache in memory.

3. Disk Storage (Data Files, . Data Dictionary, Statistical data, indices) Data Files : It stores the database.

Data Dictionary : It stores metadata about the structure of the database.

Indices : Provide fast access to data items that hold particular values.

Statistical Data : It stores statistical information about the data in the database. This information is used by query processor to select efficient ways to execute query.BACK

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Lecture 06 Overall structure of DBMS

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Lecture 07Database Users

Types of users in DBMS

1. Application programmers or Ordinary users

2. End users

3. Database Administrator (DBA)

4. System Analyst

1. Application programmers or Ordinary users Application programmers are the users who write the program. These programmers use programming tools to develop the program. RAD technology is used to write the program.

2. End Users End users are the users, who use the applications developed. End users need not know about the working, database design, the access

mechanism etc. They just use the system to get their task done. End users are of two types: a) Direct users b) Indirect users

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Contd..3. Database Administrator (DBA):

Database Administrator (DBA) is the person which makes the strategic and policy decisions regarding the data of the enterprise.

Those who provide the necessary technical support for implementing the decisions.

4.Sophisticated users Sophisticated users interact with the system by making the requests in the form

of query language. These queries are then submitted to the query processor. Query processor converts the DML statements into lower level interactions

which are understandable by storage manager. Some sophisticated users can be analyst.

5. Specialized users These users are not traditional. They write some special application programs which are not regular applications. Example: such types of applications are CAD, knowledge based and expert

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Function Of DBA1. Schema Definition

The Database Administrator creates the database schema by executing DDL statements. Schema includes the logical structure of database table (Relation) like data types of attributes, length of attributes, integrity constraints etc.

2. Storage structure and access method definition

The DBA creates appropriate storage structures and access methods by writing a set of definitions which is translated by data storage and DDL compiler.

3. Schema and physical organization modification

DBA writes set of definitions to modify the database schema or description of physical storage organization.

4. Granting authorization for data access

The DBA provides different access rights to the users according to their level. Ordinary users might have highly restricted access to data, while you go up in the hierarchy to the administrator, you will get more access rights.

5. Integrity constraints specifications

Integrity constraints are written by DBA and they are stored in a special file which is accessed by database manager while updating data.

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Client/Server Architecture

• The data processing is split into distinct parts. A part is either requester (client) or provider (server).

• The client sends during the data processing one or more requests to the servers to perform specified tasks.

• The server part provide services for the clients.

Client

Server

Request / Response

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Contd..Two tier Architecture

Two-tier Architecture consists of three components:1) User system interface2) Processing Management3) Database ManagementUser System Interface provides friendly layer of communication to make request of server and offermultiple forms of inputs and outputs.

Processing Management includes process development, process implementation, monitoring andresource services.

Database Management includes database and file services two-tier client-server design derivesits name from how it distributes work between client and server.

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Cond…Three tier architecture

• In three tier architecture the communication taken place from client to application server and then application server to database system to access the data. The application server or web server is sometimes called middle layer or intermediate layer.

• The middle layer which processes applications an database server processes the queries.

• This type of communication system is used in the large applications or the world web applications.

• On WWW all clients requests for data and server serves it. There are multiple servers used like fax server, proxy server, mail server

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Contd..

Three tier architecture

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12 Rules(Codd’s Law)

• Rule 1: Information Rule• Rule 2: Guaranteed Access Rule• Rule 3: Systematic Treatment of NULL Values• Rule 4: Active Online Catalog• Rule 5: Comprehensive Data Sub-Language Rule• Rule 6: View Updating Rule• Rule 7: High-Level Insert, Update, and Delete Rule• Rule 8: Physical Data Independence• Rule 9: Logical Data Independence• Rule 10: Integrity Independence• Rule 11: Distribution Independence• Rule 12: Non-Subversion Rule

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Lecture 08Introduction to Distributed Database

• A distributed database (DDB) is a collection of multiple, logically interrelated databases distributed over a computer network

• A distributed database management system (DDBMS) is the software that manages the DDB and provides an access mechanism that makes this distribution transparent to the users

• Implicit assumptions– Data stored at a number of sites each site logically consists of a single

processor– Processors at different sites are interconnected by a computer network – DDBS is a database, not a collection of files (i.e. relational data

model). – DDBMS is a collections of DBMSs (not a remote file system)

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Contd..

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Introduction to Data Mining

• Data mining (knowledge discovery from data) KDD

– Extraction of interesting (non-trivial, implicit, previously unknown and potentially useful) patterns or knowledge from huge amount of data.

• Alternative names

– Knowledge discovery (mining) in databases (KDD), knowledge extraction, data/pattern analysis, data archeology, data dredging, information harvesting, business intelligence, etc.

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Data Mining architecture

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What is Data Warehousing

Data

Information A process of transforming data into

information and making it available to users in a timely enough manner to make a difference

A data warehouse is a subject-oriented Integrated , time-varying , non-volatile collection of data that is used primarily in organizational decision making.

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Contd..

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MSBTE Asked Questions

• What is DBMS? Explain any two functions of DBMS. (W-07)

• Explain any one responsibility of database manager. (W-07)

• Explain the client server architecture. (W-07)• List the disadvantages of file processing system over DBMS.

(W-07)

• Define data abstraction and its level. (S-08)• What are components of DBMS? (S-08)• Explain overall structure of a DBMS. (S-08)• Explain in brief client-server architecture with example. (S-08)

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Contd..• List the advantages of DBMS. (w-08)• List the functions of database administrator. (w-08)• Define data independence. List its type. (w-08)• What is data abstraction? Explain the levels of data abstraction. (s-08)• Explain type of database users. (s-08)• What is data independence? What are its types? (s-08)• Explain advantages of DBMS over file processing system. (s-08)• Define data and BBMS. (w-9)• List different database users. (w-9)• Explain two tier and three tier client/server architecture. (s-12)• Explain three level architecture with diagram. (w-9).•