View
6
Download
0
Category
Preview:
Citation preview
Page 1
Dr.SNS RAJALAKSHMI COLLEGE OF ARTS AND SCIENCE
(AUTONOMOUS)
Accredited With “A” Grade by NAAC
An ISO 9001-2008 Certified Institution
(Recognized by UGC, Approved by AICTE, NEW DELHI and
Affiliated to Bharathiar University, Coimbatore)
2012-2013
DEPARTMENT OF COMMERCE WITH COMPUTER APPLICATIONS
RELATIONAL DATABASE MANAGEMENT SYSTEMS
PREPARED BY
DEPARTMENT OF COMMERCE WITH COMPUTER APPLICATIONS
Page 2
Relational Database Management System
Objective: On successful completion of this subject the students should have Knowledge on database management systems and build a solid foundation for advanced studies in database area. UNIT I:
Introduction: purpose of the database system – view of data – data models – database languages – transaction management – storage management – database administrator – database users. Entity-Relationship
models: basic concepts – design issues – mapping constraints – keys – E-R diagram – weak entity sets – Extended E-R features.
UNIT II:
Relational Model: Structure of relational databases – the relational algebra - the tuple relational calculus - the domain relational calculus. Relational Database Design: Pitfalls in relational-database design – decomposition – normalization using fundamental dependencies - Distributed Databases: distribution transaction model – commit protocols – concurrency control. UNIT III:
Oracle Tables: DDL: Naming Rules and conventions – Data Types – Constraints – Creating Oracle Table – Displaying Table Information – Altering an Existing Table – Dropping, Renaming, Truncating Table – Table Types – Spooling – Error codes. UNIT IV:
Working with Table: Data Management and Retrieval: DML – adding a new Row/Record – Customized Prompts – Updating and Deleting an Existing Rows/Records – retrieving Data from Table – Arithmetic Operations – restricting Data with WHERE clause –Sorting – Revisiting Substitution Variables – DEFINE command – CASE structure. Functions and Grouping: Built-in functions –Grouping Data. Multiple Tables: Joins and Set operations: Join – Set operations. UNIT V:
PL/SQL: A Programming Language: History – Fundamentals – Block Structure – Comments – Data Types – Other Data Types – Declaration – Assignment operation – Bind variables – Substitution Variables – Printing – Arithmetic Operators. Control Structures and Embedded SQL: Control Structures – Nested Blocks – SQL in PL/SQL – Data Manipulation –Transaction Control statements. PL/SQL Composite Data Types: Records – Tables – Varrays.
Page 3
Text Book(s): 1. Henry F.Korth, Abraham Silberschatz & S. Sudarshan, “Database System Concepts”, Tata McGraw-Hill, 2010. (Unit-I, II) 2. Nilesh Shah, “Database Systems Using Oracle”, 2nd edition, PHI, 2008(Unit-III, IV, V) Reference Book(s): 1. Rajesh Narang, “Database Management Systems”, PHI, 2006. 2. Gerald V.Post, “Database Management Systems”, Tata McGraw-Hill, Sixth Reprint, 2008
Page 4
UNIT I
Introduction
Database Management System (DBMS)
DBMS contains information about a particular enterprise
Collection of interrelated data
Set of programs to access the data
An environment that is both convenient and efficient to use
Database Applications:
Banking: all transactions
Airlines: reservations, schedules
Universities: registration, grades
Sales: customers, products, purchases
Online retailers: order tracking, customized recommendations
Manufacturing: production, inventory, orders, supply chain
Human resources: employee records, salaries, tax deductions
Databases touch all aspects of our lives
Purpose of Database Systems
In the early days, database applications were built directly on top of file
systems
Drawbacks of using file systems to store data:
Data redundancy and inconsistency
Multiple file formats, duplication of information in different files
Difficulty in accessing data
Need to write a new program to carry out each new task
Data isolation — multiple files and formats
DATA BASE SYSTEM
Database system is nothing more than a computer-based record keeping system
(i.e.) a system whose overall purpose is to record and maintain information.
The database system involves four major components. They are data, hardware,
software and users.
Page 5
Database Management System
Fig: Simplified picture of a database system
Data
The data stored in the system is partitioned into one or more databases.
Integrated:
The database can be thought of as a unification of several distinct files,
with the redundancy among those files eliminated.
Example: Combination of EMPLOYEE and ENROLLMENT data files.
Shared:
Individual pieces of data in the database can be shared among different
users that is many users can have access to the same piece of data.
Example: The department information in EMPLOYEE file
would be shared by users in the personal department,
education department etc.
Hardware
The hardware consists of the secondary storage device disks, drums,etc…
Software
It is a set of programs used to accomplish a task.
Users
*application programmers
*end-users
*DBA
1.Application programmers
Application programmer is responsible for writing application programs
that use the database.
2.End-users
Page 6
End-users access the database from a terminal.
3.Database Administrator
The person who has such control over the system is called DBA.The
main functions of DBA are
*Schema definition
*Storage structure and access-method definition
*Granting and physical-organization modification
*Integrity-constraint specification
These are the various components of a database system.
Operational data
A database is a collection of stored operational data used by the application systems of some
particular enterprise.
Examples. Manufacturing company, Bank, Hospital, University, Government
department etc.
Example for the illustration of operational data
Consider the manufacturing company where the enterprise will wish to
retain information about the projects it has on hand; parts used in those projects; the suppliers
who supply the parts; the warehouses in which the parts are stored; the employees who work
on the projects etc.,
These are the basic entities about which data is recorded in the database. In general
there will be associations or relationships linking the basic entities together(entity is any
distinguishable object).
For example, there is an association between suppliers and parts that is each supplier
supplies certain parts and conversely each part is supplied by certain suppliers etc..
Fig: An example of operational data
The figure illustrates
1. Most of the associations are between two entities or more than that
ex., arrow connecting suppliers-parts-projects
Here supplier s2 supplies part p4 to project j3.
2. The example also shows one arrow involving only in one type of entity (parts)
ex., some parts are components of other parts (a screw is a component of a huge assembly
or char etc..)
3. Some entities may be associated in more than one relationship
Projects Suppliers
Department
s
Parts Employees Warehouses
Locations
Page 7
Ex., projects and employees are linked in two relationships
A. the employee works on the project
B .the employee is the manager of the project
This example clearly illustrates operational data and its functions.
Data Independence
The ability to modify a schema definition in one level without affecting a schema in
the next higher level is called data independence.
Two types of data independence stated are
1. Physical data independence
Physical data independence is the ability to modify the physical schema
without causing application programs to be rewritten.
Example,
Modifying the structure of the database using ALTER command etc.
2. Logical data independence
Logical data independence is the ability to modify the logical schema
without causing the application programs to be rewritten.
Example,
Modifications such as adding new columns or field to the database.
Most of the modifications are done by the DBA and the types of change
that the DBA wish to make may be explained with the help of the
following definitions:
Stored field: Stored field is the smallest unit of data stored in the database.
Ex., database containing information about parts would probably include a stored field type
called part number etc.
Stored record: Stored record is a named collection of associated stored fields.
Stored file: Stored file is the collection of all occurrences of one type of stored
record.
Similarly if a data type of the stored field has to be changed is also done by
Data.
The data storage may be in any of the following form.
1. Representation of numeric data
Data may be stored in internal arithmetic form or as a character string.
2. Representation of character data
A character field may be stored in any of several character codes
(eg.EBCDIC,ASCII..)
3. Units for numeric data
The units in a numeric field may change.Ex.,from inches to centimeters
4. Data coding
In some situations it may be desirable to represent data in storage by coded values.
Ex., the value for part color=RED can be interpreted as 1=’RED’.
5. Structure of stored records
Two existing types of stored record may be combined into one. For ex., the record
types(part number, color) and (part number, weight) may be integrated to give
(part number,color,weight).
Also a single type of stored record may be split into two. For ex.,(part
number,color,weight) may be broken down into (part number, color) and (part
number, weight).
6. Structure of stored fields
Page 8
A given stored file may be physically implemented in storage in a wide variety of
ways.
For ex: storing the file in single storage volume or spread across several volumes.
The above fact implies that the database is able to grow without affecting existing
applications.
Architecture for a Database system
The architecture is divided into three general levels; they are internal, conceptual, external
levels,
…………………………….
External level
(Individual user views)
Conceptual level (Community
user view)
Internal level (Storage
view)
Fig: Three levels of architecture
Internal level(Physical level)
The storage view is described by means of the internal schema which not only
defines the various stored record types but also specifies what indexes exist, how
stored files are represented, what physical sequence the stored records are in and so
on.
Conceptual level (Community logical level)
This level is the representation of the entire information content of the database.
External level(user logical level)
This level is closest to the users and is concerned with the way the data is seen by
the individual users.
For example,
A user from the Personnel Department might view the details of employee and department
and nothing else.
Detailed System architecture
Page 9
fig: Database system architecture
Mappings
The mappings involved in the architecture are conceptual/internal mapping and
external/conceptual mappings.
The conceptual/internal mapping defines the correspondence between the
conceptual view and stored database.
The external/conceptual mapping defines the correspondence between a particular
external view and the conceptual view.
Database administrator(DBA)
Thus the DBA is responsible for the overall control of the system in technical level. The
major tasks of DBA are
Defining the conceptual schema or schema definition
Storage structures and access-method definition
Schema and physical organization modification
Granting of authorization for data access
Integrity constraint specification
DBMS
The DBMS is the software that handles all access to the database. Its functions are as
follows
A user issues an access request using some particular data sub language
The DBMS intercepts that request and analyses it.
The DBMS inturn,intercepts the external schema for that user, the corresponding
external/conceptual mapping, the conceptual schema, the conceptual/internal
mapping, the storage structure definition.
The DBMS executes the necessary operations on the stored database
Page 10
The diagrammatic representation of the major functions of DBMS and its components.
Distributed databases
Distributed processing means that distinct machines can be connected
together into communication network such as the Internet, so that the single data-
processing task can span several machines in the network.
For example, consider a banking system in which the customer accounts database is
distributed across the bank branch offices, such that each individual customer account
record is stored at the customer’s local branch.
Advantages
Efficiency of local processing
Data sharing
Disadvantages Overhead may be quite high
Technical difficulties
Page 11
Storage structures and its purposes.
The main idea behind data maintenance is for future reference and it has to be stored for the
storage and access of data ,various techniques like sequential ,direct access etc. exists.
Once the data is stored in the memory in internal level(physical storage) then it is
accessed through DML operations.
The component responsible for this internal/physical conversion is called an access
method.
The access method consists of a set of routines whose function is to conceal all
device-dependent details from the DBMS and to present the DBMS with a stored
record interface.
Fig: The stored record interface
The stored record interface allows DBMS to view the storage structure as a collection
of stored files each consisting of all occurrences of one type of stored record. The
DBMS knows
What stored files exist
The structure of the corresponding stored record
The stored fields on which it is sequenced
The stored field which can be used for direct access etc.
This information will be specified as part of the storage structure definition.
The DBMS does not know
a) Anything about physical records
b) How sequencing is performed
c) How direct access is performed
These informations are specified to the access method not to the DBMS.
Also, when a new stored record occurrence is first created and entered into the database, the
access method is responsible for assigning it a unique stored record address(SRA).
How data are stored in the physical storage?
Page 12
There are various possible representations of data within
the memory and some of them are explained here.
Consider the
following example.
The above example is the simplest form of data representation containing
only five record occurrences with unique supplier number.
If the suppliers are 10000 rather than five and located in only 10 different
cities then the storage will be wasted specifying the 10 cities among 10000
suppliers.
Then the pointer is specified from the supplier file to the city file by
separating the city attribute alone to a file.
The following is another form of data the representation
Supplier file
City File
City
Athens
London
Paris
indexed on city
An example,”Find all suppliers in a given city”,when this query is placed then the result is
retrieved quite easily from the database if represented as above that is in indexed form.
DATA STRUCTURES AND CORRESPONDING OPERATORS
The range of data structures supported at the user level is a factor that critically affects many
componenets of the system
Relational approach
Hierarchical approach
Network approach
S# Sname Status City
S1 Smith 20 London
S2 Jones 10 Paris
S3 Blake 30 Paris
S4 Clark 20 London
S5 Adams 30 Athens
S# Sname Status City-ptr
S1 Smith 20
S2 Jones 10
S3 Blake 30
S4 Clark 20
S5 Adams 30
City Supplier ptr
Athens
London
paris
S# Sname Status
S1 Smith 20
S2 Jones 10
S3 Blake 30
S4 Clark 20
S5 Adams 30
Page 13
The relational approach
The relational approach uses a collection of tables to represent both data and the
relationships among those data.
Sample relational database
Bank customer
Accounts
account-no balance
A-101
A-215
A-102
A-305
A-201
A-217
A-222
500
700
400
350
900
750
700
For example, customer Johnson whose social-security-no. is 192-83-7465 lives on Alma in
Palo Alto and has 2 accounts A-101 with balance 500,a-201 with balance 900.Also smith and
Jhonson shares A-201 account.
Network model
Data in the network model are represented by collections of records and
relationships among data . The relationships among data can be represented
by links, which can be viewed as pointers
Sample network databases
Hierarchical Model
This form of data representation is similar to network model in the sense that
records represent data and relationships among data and links.
Customer name social-security-no. customer-street customer-city account-no.
Johnson 92-83-7465 Alma Palo Alto A-101
Smith 019-28-3746 North Rye A-215
Hayes 677-28-9011 Main Harrison A-102
Turner 182-73-6091 Putnam Stamford A-305
Johnson 192-83-7465 Alma Palo Alto A-201
Jones 321-12-3123 Main Harrison A-217
Lindsay 336-66-9999 Park Pits field A-222
Smith 019-28-3746 North Rye A-201
Johnson 192-83-7465 Alma Palo Alto A-101 500
A-215 700 Smith 019-28-3746 North Rye
Page 14
It differs from the network model in that the records are organized as
collection of trees rather than graphs.
Advantages of using DBMS
Many enterprises choose to store its operational data in an integrated database
because it provides the enterprise with centralized control of its operational data,
which is most valuable.
DBA has the central responsibility over operational data.
Advantages if data is stored under centralized control.
QUESTIONS
ONE MARKS:
1. RDBMS refers to _________database
a)Rational b)Ring c)Relational d)Region
2. Data values stored in a database must satisfy certain______
a) Rules b)Constraints c)Conventions d)Data
3. The collection of information stored in a database at a particular moment is called
_________ of the database
a)Schema b)View c)instance d)Data independence
4.Overall design of the database is called the database__________
a)View b)Schema c)Abstraction d)Independence
5. ________ models are used in describing data at logical and view level
a)Object based b)Physical c)Record based d)Functional
6. The collection of basic object is called as __________
a)attribute b)entity c)relationship d)variables
7. The relational model uses collection of _________
a)records b)tables c)columns d)trees
8. Data in the network model uses collection of _______
a)Trees b)Tables c)Columns d)Links
9. A data dictionary contains _______
a)data b)data about data c)tables d)records
10. A __________ is a collection of operations that performs a single logical function in a
database application
a)data b)transaction c)file d)table
11.The__________ is responsible for the interaction with file manager
a)DML b)DDL c)Storage manager
12. Overall logical structure of a database can be expressed graphically by ____
Page 15
a)Rectangles b)Ellipses c)ER diagram d)Diamonds
13.A person who have central control over the system is called ________
a)Storage manager b)File manager c)Application programmers d)DBA
14. __________ one computer professionals who interact with the system through DML calls
a)naïve users b)application programmers c)specialized uses d)sophisticated users
15. _________ users interact with the system without writing programs
a) specialized b)naïve uses c)sophisticated users d)application programmers
16. __________ is a language that enables users to access or manipulate data
a)DDL b)DML c)Database d)Procedure
17. __________ express the number of entities to which another entity can be associated via
relationship set
a)attributes b)mapping cardinalities c)relationship d)schema
18. An entity in A is associated with at most one entity in B then it is a ______ relationship
set
a)one to one b)many to one c)many to many d)one to many
19.An entity in A is associated with any number of entities in B and entity in B is associated
with any number of entities in A then it __________ relationship
a))one to one b)one to many c)many to many d)many to one
20.An entity set that does not have sufficient attributes to from a primary key then it is
________ entity set
a)strong b)weak c)strong and weak d)relationship set
21. Data that is processed and is relevant
a)Data base b)Information c) Data d) Knowledge
22. In E-R Diagram the entities are represented by
a) Rectangular box b) Ellipse c) Triangle d) Square
23. A database schema is specified by a special language called
a) DDL b) DML c)Query language d) none
24. Single column is used as unique identifier is known as
a)Primary key b) Foreign key c) Super key d) Candidate key
25. In a database there are entities that cannot exists by themselves. Such entities are known
as ________ entities.
a) Weak b) Strong c)Network d)Relational
FIVE MARKS:
1. List the difference between file system and database system.
2. Explain the mapping constraints briefly.
3. Explain the purpose of the database system.
4. What is mean transaction processing?
Page 16
5. Explain E-R model with example.
6. What are the important functions of RDBMS?
7. Mention the types of attributes.
8. Write short notes relationships
9. Explain the difference between physical and logical independence.
10. Illustrate the difference between
11. a)three levels of abstraction & b)between a schema and instance
12. Explain the distinctions among primary key, candidate key and super key
13. Differences between weak and strong entity set
14. Analyze the concept and merits of RDBMS.
15. Write short notes on database users
EIGHT MARKS:
1. Discuss categories on data models.
2. Explain the transaction management.
3. Create an E-R diagram to represent your college.
4. List the Responsibilities of a database manager?
5. We can convert any weak entity set to a strong entity set by simply adding
appropriate attributes. Why then do we have weak entity set.
6. Explain the concept and importance of views
Recommended