lecture by prof.dr.s.sridhar 1 database technology by dr.s.sridhar, ph.d.(jnud), raci(paris, nice),...

Lecture by Prof.Dr.S.Sridhar

1

DataBase Technologyby

Dr.S.Sridhar, Ph.D.(JNUD),RACI(Paris, NICE), RMR(USA), RZFM(Germany)

DIRECTORARUNAI ENGINEERING COLLEGETIRUVANNAMALAI


2

DBMS CONCEPTSData Base

Management Systems

• Examples of Databases• Files & DB – Systems• Advantages of DBMS• Attributes / Entities• Normalization in RDBMS• RDBMS & Examples• SQL in DB & Examples• Entity-relationship model• 3NF• Students/s DB – Case Study• Data Base Security / Backups


3

• What’s Database System ?- It is nothing but a computerized record keeping system.- The DB itself can be regarded as electronic filing cabinet.- It is a collection of files.

The user of the system will have the following facilities :• Adding New, empty files to the DB.• Inserting new data into existing files.• Retrieving data from existing files.• Deleting data from existing files.• Removing existing files, empty or

otherwise, from the DBData base is a collection of files.Data base is a collection of records.Data base is a collection of fields.


4

• The above file is referred as ‘Table’ in RDBMS – Sense.

• Call this table as “CELLAR”• This contains many records.• Each record has fields.• Here

• is a record • The values inside the tableare called “ Field values”

BIN

WINE PRODUCER YEAR BOTTLES

READY

2 Chardonnary Buena Vista 1992 1 1994

3 Chardonnary Geyser Peak 1992 5 1994

6 Chardonnary Stonestreet 1991 4 1993

12 Jo.Riesling Jekel 1993 1 1994

21 Fune ‘ Blanc Ch.St.Jean 1992 4 1994

22 Fune ‘ Blanc Geyser Peak 1991 2 1993

30 Cab.Saurignon

Jekel 1986 12 1995

43 Cab.Saurignon

Jekel 1990 2 1993

45 Pinot Noir Buena Vista 1989 9 1998

50 Pinrot Noir Buena Vista 1990 2 1998

BIN

WINE

PRODUCER

YEAR

BOTTLES

READY

Fields


5

Retrieve Data (Query Language)

SELECT WINE, BIN, PRODUCERFROM CELLARWHERE READY = 1995 ;

RESULT

is the command used to Retrivefrom which table ( file )

Condition

INSERT:INSERTINTO CELLAR ( BIN, WINE, PRODUCER )

VALUES ( 53, ‘Pinot Noir’, ‘Saintsbury’);UPDATE:

UPDATE CELLARSET BOTTLES = 4WHERE BIN = 3;

WINE

Cab.Saurignon

BIN

30

PRODUCER

JEKEL


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DELETEDELETEFROM CELLARWHERE BIN = 2;

Thus, the commands like, SELECT, INSERT, UPDATE and DELETE are actually the examples of Database Query Language.

SQL – Structured Query Language

Remarks :- One should be very careful. Whenever DELETE or

UPDATE operations are done in the DB.

Here, - Retrieving any amount of fields for

a particular record is done .- Inserting into file for a particular field(s) with values is done.- Updating is for a particular field in

a record is done.- Deleting is done for a record under

a matching condition.


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(DBMS)Data Base Management System

Application ENDPrograms USERS

Major Components:* Data* Hardware Simplified View * Software of Data base System* Users

An Overview of Database Management

Data Base


8

Examples of Data Bases: Financial Database Personnel Database ( Employee) Payroll Database Accounting Database Inventory Database Management Information Database Library Databaseand so on.

Examples of DBMS (Data Base Management System) ORACLE INFORMIX INGRESS SYBASEand so on.

What ‘s Data ?It is the meaning full information stored in computer system.

Two Kinds Integrated Shared

Integrated, means that the Database can be thought of as a unification of several otherwise distinct data files, with any redundancy among those files wholly or partially.


9

ExampleA Database containing both the files.EMPLOYEE

IDNONameAddressDepartmentSalariesPhone No.Permanent Address

and a training file.TRAINING

IDNOCourse a HeadedCourse DetailsCourse FeesLocation of CourseFeedbackGrade Offered

Shared Database means that individual pieces of data in the database can be shared by several different users.

For example from the file ‘EMPLOYEE’,The general details can be utilised by Personnel department.The salary details may be utilized by Financial department. All

done in shared manner.and so on.


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Hardware Consisting of Secondary storage volumes that are used to

hold the stored data with associated I/O devices(Disk drives etc), Devices Controllers, I/O channels,etc.

The Processors and associated main memory that are used to support the execution of the Database system software.

Software Consisting of Database Manager (DB Manager) or more

commonly used term as ‘DBMS’, Data Base Management System.

Additional utilities like Application development tools, design aids, report writers and so on.

Example: Oracle, Informix, Sybase,etc.

Users Application Programmers, who are

responsible for writing programs to access the Database for Insert, Update, Delete, Query, Reports etc.

End users who are really accessing the database for queries / data entry / report generation etc.


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What is Database ? It is a collection of ‘Persistent data’ that is used by

the application systems of some given enterprise.

Input data : refers the information entered into the systems for the very first time ( typically from a terminal or workstation). It may be part of persistent data but it is not initially part of the databases

Output Data : refers for messages and results coming out from the system ( typically printed or displayed on a screen). Again such information is derived from persistent data but it is not itself considered to the part of the database.

Enterprise (Egs) Persistent Data (Egs)************ **************** A Manufacturing * Product Data

Company A Bank * Account Data A Hospital * Patient Data A University A govt. Dept.


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Advantages of Databases Compactness ( No read for Voluminous papers) Speed ( for retrieval of Queries / Reports etc) Currency (Accurate, up-to-date information is

available on demand anytime ) Centralized control of data.

The foregoing benefits apply even more force in multi – user environment, of course, where the database is likely to be much larger and much more complex then in the single-user-case.

Redundancy of data can be avoided. In consistency can be avoided to some extent. The data can be shared by many users. Standards can be enforced. Security restrictions can be applied. Integrity can be maintained. Conflicting requirement can be balanced.


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RDBMS (Relational Data Base Mgmt. System)

Relational Systems are such that

1. The data perceived by users as tables.

2. The operators are at users’ disposal.(eg) Data retrieval – are operators that qurerate new tables from old and those operators include atleast ‘SELECT’, PROJECT and JOIN.

EXAMPLE :

DEPT

EMP

DEPT# DNAME BUDGET

D1

D2

D3

Marketing

Development

Research

10M

12M

5M

EMP#

ENAME DEPT Salary

E1

E2

E3

E4

John

Marsal

Lemark

Cheng

D1

D1

D2

D2

40k

25k

42k

35k


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SELECT – Operation extracts specified rows from a table.

PROJECT - Operation extracts specified columns from a table

JOIN - Operation joins together two tables on the basis of common values in a

common column.

Apply the above operations on DEPT & EMP Tables

SELECT DEPTs WHERE BUDGET > 8M

Result

(Specified Rows)

PROJECT DEPTs OVER DEPT#, BUDGET

Result

(Specified Columns)

JOIN DEPTs and EMPs OVER DEPT#

Result

Common

Rows

Common

Columns

DEPT# DNAME BUDGET

D1

D2

Marketing

Development

10M

12M

DEPT# BUDGET

D1

D2

D3

10M

12M

5M

DEPT#

DNAME BUDGET

EMP#

ENAME

SAL

D1

D1

D2

D2

Marketing

Marketing

Development Development

10M

10M

12M

12M

E1

E2

E3

E4

John

Marsal

Lemark

Cherq

40K

25K

42K

35K


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Entity – Attributes –Relationship modelsConcept Information Examples

Definition

ENTITY A Distinguishable - Supplierobject - Part

- Person- Purchase Orderand so on

PROPERTY A piece of information - Supplier number to describe an entity - Shipment Qty

- Person height- P.O.data etc.

RELATIONSHIP An entity that serves to - Shipment interconnect 2 or more (Supplier-part)entities - Assignment

(Emp-Dept.)Here Note

1) Shipment is RELATIONSHIP between supplier and part.R

RSimilarly for Assignment.

Supplier Part


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Entity / Relationship diagram (Example)-----*---------*----------*--------*---------*Entities : Department, Employee, DependentRelations : Dept-Emp, Emp-depAttributes : ( to employee)

Emp#, Ename,Salary

First MN Last (Group item)

Department

Dept-Emp

Employee

Emp

Ename

First MN Last

Salary

Emp-Dep

Dependent


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Properties:

Entities have properties : (Known as attributes). Take the case of Employee whose properties are Emp#, Ename and Salary. (all these are attributes).

Simple a Composite: Emp# is simple

But Ename contains First, MN and Last, three simple items groped together to address Ename. Such type of attributes are ‘Composite’.

Key :

It is one of the uniquely defined attributes. For eg. Emp# is unique and that is called ‘key’ to access the other properties of the entity employee, like Ename and Salary.

Key

Emp# Ename Salary


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Types of Relations1 – 1 (One to One)1 – M (One to Many)M – 1 (Many to One)M – M ) (Many to Many)

Examples ( 1-1)For every employee there is only one seat

R

(1-1)In an organization.(1-M) R

;.;

(M-1) R

::;

(M – M)

Emp Seat

Supplier

Customer1

Customer-m

Student1

Student-m

Teacher

Suplier1…….m

Customer11………m


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Many Examples of Attributes / Entities & RelationsExample 1:

Book –Student BOOK-STD R > R R< STD -BOOK

Entities : Book, StudentRelation : BOOK-STD and STD-BOOK

Attributes of Book Attributes of Student Author RollNo Title ExamNo Publisher Name Year Class ISBN Number Address Number of pages Phone No Price Remarks Printer Location of printing Edition-Nature Remarks

Book Student


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Example 2 ( R )Part-Sup

( R )

Sub-part ( R )

Entities : Part, SupplierRelations : Part-Sup and Sub-part

Attributes of part Attributes of Supplier

PartNo Supplier code Description Supplier address Qty Supplier phone Unit price Supplier location Opening balance Delivery time Parts-new Address demand Net balance Warranty Period Remarks Remarks

Part Supplier


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Example 3:Stud-fac R R RFac-stud

Entities : Student and FacultyRelations : Stud-fac and Fac-stud

Attributes of Student Attributes of Faculty RollNo Facuty ID ExamNo Name Name Classes Handling Class Qualification Address Designation PhoneNo Address Faculty Division Phone No Remarks Students Related for

Advising

Student Faculty


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NORMALIZATION in RDBMS

The logical design considered are:

S ( S#, SNAME, STATUS, CITY)

PRIMARY KEY ( S#)

P (P#, PNAME,COLOR, WEIGHT, CITY)

PRIMARY KEY (P#)

SP (S#, p#,QTY)

PRIMARY KEY (S#, P#)

FOREIGN KEY ( S#) REFERENCE S

FOREIGN KEY (P#) REFERENCE P

SCP (Relation) TableS# CITY P# QTY

S1

S1

S1

S1

S1

S1

S2

S2

S3

S4

S4

S4

London

London

London

London

London

London

Paris

Paris

Paris

London

London

London

P1

P2

P3

P4

P5

P6

P1

P2

P2

P2

P4

P5

300

200

400

200

100

100

300

400

200

200

300

400


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From the table we find ‘Redundancy’ of data. So a good design principle is “ One fact in one place” ((ie) avoid redundancy). How to do this ? That process is known as “ Normalization”. There are 3NF (Normal forms – NF).Namely First NF (1NF)

Second NF (2NF)Third NF (3NF)

1NF:Every Normalized relation is in 1NF if and only if, if satisfied the condition that it contains scalar values ONLY.

ExampleFIRST (S#, STATUS, CITY, P#, QTY)PRIMARY KEY (S#, P#)

Functional Dependencies in relation FIRST

QTY

CITY

STATUS

S#

P#


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Sample Tabulation of FIRST

Now problems, We face with

INSERT DELETE UPDATE

S# STATUS CITY P# QTY

S1

S1

S1

S1

S1

S1

S2

S2

S3

S4

S4

S4

20

20

20

20

20

20

10

10

10

20

20

20

London

London

London

London

London

London

Paris

Paris

Paris

London

London

London

P1

P2

P3

P4

P5

P6

P1

P2

P2

P2

P4

P5

300

200

400

200

100

100

300

400

200

200

300

400


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Problems with INSERT

- For examples, while inserting S5 after S! or S2 or S3 or S4, Confusion arises, Where to insert ?!- Insert a status after 20 – problem !

- Insert a city after LONDON – problem !- Insert P# after P2 – Problem !

DELETEWhile deleting some record,One should be more careful.

Now delete a record corresponding to S# = 1.This will delete all records corresponding to S# = 1, whereas user may NOT mean this !

Similarly,

UPDATE :Update city for S# = 2This will update all city values, corresponding to S# = 2, whereas user does not mean this !


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Second Normal Form :A relation is in 2NF if and only if is in !NF and every non-key attribute is irreducibly dependent on the primary key.

ExampleSECOND (S#, STATUS, CITY)

and SP(S#, P#, OTY)

Functional Dependencies in relationSECOND AND SP

SECOND

SAMPLE TABULATION OF SECOND AND SP

CITY

S#

STATUS

QTY

S#

P#

S# Status City

S1

S2

S3

S4

S5

20

10

10

20

30

London

Paris

Paris

London

Athens

S# P# QTY

S1

S1

S1

S1

S1

S1

S2

S2

S3

S4

S4

S4

P1

P2

P3

P4

P5

P6

P1

P2

P2

P2

P4

P5

300

200

400

200

100

100

300

400

200

200

300

400


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INSERT :

Eventhough S5 is not supplying any parts, we can insert the information that S5 is located in Athens, in SECOND.

DELETE :

While deleting the shipment connecting S3 and P2 in SP, we do NOT loose information that S3 is located in PARIS.

UPDATE :

In the revised structure, the city for given supplier appears once not many times. Thus S# CITY redundancy is eliminated. For example we can change for S1, the city as Amsterdam from London. This way updation is also possible in 2NF.

Third Normal Form (3NF):

A relation is in 3NF if it is in 2NF and every non-key attribute is non-transitively dependent on the primary key.

This increases the data independance,.


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Example:Key Key

Sample Tabulation of SC and CSThe above relation SC and CS are in 3NF.

Whereas, SECOND is not in 3NF.

SECOND

Thus SECOND (S#, STATUS, CITY) is tabulated in 3NF asSC(S#, CITY) and CS (CITY, STATUS)

S# CITY

S1

S2

S3

S4

S5

London

Paris

Paris

London

Athens

CITY STATUS

Anthen

London

Paris

Rome

30

20

10

50

S# STATUS CITY

S1

S2

S3

S4

S5

20

10

10

20

30

London

Paris

Paris

London

Athens


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Database Security & Back-ups

Security problems : Legal, Social and ethical aspects

Eg : does a person making the request

say for customer’s credit

- have a legal right to the requested information.

Physical Controls

Eg : Computer or Terminal room locked !

Or otherwise guarded ? !

Policy Questions

Who should have access ? !

To what level ? !

Operational Problems

- Password is used. Then

- How are the passwords Rept secrete ?

- How often they are changed ?


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Hardware Control- Whether the processing unit has any

security measures,such as storage protection keys or privileged operation mode ?

Operating System Security- Whether the O /S erase the contents of storage ? ! and Data files ? !

Issues Concerned with DBMS- Whether the DBMS has the concept of ownership ?

Examples of Discretionary Access control Create Security Rule SR3

GRANT RETRIEVE (S#, SNAME, CITY),

DELETE ON S WHERES.CITY = ‘LONDON’TO JIM, FRED, MARY

ON ATTEMPTED VIOLATION REJECT;


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CREATE SECURITY RULE EX1:GRANT RETRIVE (S#, SNAME, CITY)ON STO JAC, ANNE, CHARLEY;

CREATE SECURITY RULE EX4:

GRANT RETRIVE (S#, SNAME)ON S WHERE S. STATUS > 50TO JAC, PAVL;

CREATE VIEW SSS AS(S.S#, S.NAME) WHERES.STATUS > 50;

Request Modification :

DEFINE PERMIT RETRIEVE ON P TO U WHERE P.CITY = “London”

RETRIEVE (P.P#, P.WEIGHT)WHERE P.COLOR = “Red”

RETRIEVE (P.P#, P.WEIGHT)WHERE P.CITY = “London”


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Back – ups:Daily Back-up

After the day work of all transactions, copying the entire system files / data files on a floppy, disk (CD), or a tape depending on the size of total volume.

Weekly back-upMonthly back-upYearly back-upIn DBMS – Mirroring concept as

back –up.Stand-by server as back-upCD- Server as back –upSoftware, specially in Oracle like

RDBMS, auto back-up and retrieval systems.


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SQL – Language

CREATE TABLE

( S# S# NOT NULL, P# P# NOT NULL, QTY QTY NOT NULL,

PRIMARY KEY (S#) REFERENCE S

ON DELETE CASECADE

ON UPDATE CASCADE,

CHECK(QTY > 0 AND QTY < 5001));

This is to create a table with attributes S#, P#, QTY, all NOT NULL values and the primary key is S# also, check the condition while creating the table itself whether QTY is > 0 and QTY < 5001.

Here CASCADE is used as an Option.

ALTER TABLE S ADD COLUMN DISCOUNT

INTEGER

DEFAULT – 1;

Here we can alter the table S by adding a new column namely DISCOUNT which is an integer quantity with default value = -1.


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DROP TABLE S;

This will drop the created table S from the database.

Data Manipulation (Retrieval operations)

(called DML)

SELECT P.COLOR, P.CITY

FROM P

WHERE P.CITY < >’PARIS’

AND P.WEIGHT > 10;

-------------------------------------------------------------------

SELECT DISTINCT P.COLOR, P.CITY

FROM P

WHERE P.CITY < > ‘PARIS’

AND P.WEIGHT > 10;

------------------------------------------------------------------

SELECT P.COLOR, P.CITY

FROM P

WHERE P.CITY < >’PARIS’

AND P.WEIGHT > 10;

ORDER BY CITY DESC;


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SELECT P.P#, P.WEIGHT * 454 AS GMNTFrom P;-------------------------------------------------------------------SELECT * FROM S;-------------------------------------------------------------------SELECT S.S#, S.NAME, S.STATUS, S.CITY,

P.P#, P.NAME, P.COLOR, P. WEIGHT,

FROM S, PWHERE S.CITY = P.CITY;

-----------------------------------------------------------------S JOIN P USING CITY

------------------------------------------------------------------SELECT DISTINCT S.CITY AS SCITY,

P. CITY AS PCITYFROM S JOIN SP USING S# JOIN P USING P#;

-------------------------------------------------------------------SELECT COUNT(*) AS NFROM S;-------------------------------------------------------------------SELECT MAX (SP.QTY)AS MAXQ,

MIN (SP.QTY)AS MINQFROM SP

WHERE SP.P# = ‘P2’;


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Update OperationsINSERTINTO P (P#, PNAME, COLOR, CITY)VALUES (‘P8’, ‘Sprocket’,’pink’, ‘Nice’);

-------------------------------------------------------------------INSERT

INTO TEMP(S#, CITY)SELECT S.S#, S.CITYFROM SWHERE S.STATUS > 15;

-------------------------------------------------------------------DELETE

FROM SPWHERE ‘London’ =

(SELECT S.CITYFROM S

WHERE S.S# = SP. S#);-------------------------------------------------------------------All or Any conditionsSELECT DISTINCT PX.NAME

FROM P AS PXWHERE PX.WEIGHT > ALL

( SELECT PY.WEIGHTFROM P AS PYWHERE PY.COLOR = ‘Blue’);


37

Exercises ON SQL

1) CREATE TABLE ( S# S# NOT NULL,

P# P# NOT NULL, QTY QTY NOT NULL)

Ans

2) CREATE TABLE ( S# S# NOT NULL,

P# P# NOT NULL, QTY QTY NOT NULL)

PRIMARY KEY (S#) REFERENCE S

CHECK (QTY >0 NAD QTY <= 20));

Ans

S# P# QTY

4532

4533

4534

4535

123

234

345

567

10

20

40

5

S# P# QTY

4532

4533

4535

123

234

567

10

20

5


38

3) ALTER TABLE S ADD COLUMN DISCOUNT INTEGER DEFAULT

–1;Ans

4) DROP TABLE S;( Then the table S will NOT be in DB)

DATA MANIPULATION1) SELECT S.P#, S.QTY FROM S

WHERE S.QTY < > 20AND S.P# > 500 ;

Ans

2) SELECT DISTINCT S.S#, S.P#, S.QTYFROM SWHERE S.QTY < > 20AND S,P# > 500;

Ans

S# P# Qty Discount

4532

4533

4535

123

234

567

10

20

5

-1

10

5

S# P# QTY

4535 567 5

S# P# QTY

4535 567 5


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3) SELECT DISTINCT S.S#, S.P#, S.QTY

S. Discount FROM S

WHERE S.QTY < 5

AND S,P# > 125

ORDER BY S# DESC;

Ans

4) SELECT S.S#, S.P#, S.QTY * 10 AS

QTY2 FROM S

WHERE DISCOUNT > 0;

Ans

5) SELECT * FROM S;

Ans

S# P# QTY Discount

4533 234 20 10

S# P# QTY QTY2

4533

4535

234

567

20

5

200

50

S# P# Qty Discount

4532

4533

4535

123

234

567

10

20

5

-1

10

5


40

6) SELECT S.S#, S.P#, S.QTY,P. P#, P.NAMEFROM S, PWHERE S.P# = P.P# ;

S Ans ( input)

Answer

7) S JOIN P USING P#Answer is the same as 6.

.X. in this case only

S# P# Qty Discount

4532

4533

4534

4535

123

234

345

567

10

20

40

5

-1

10

-1

5

P# PNAME

4532

4555

4535

4534

NUT

BOLT

SCREEN

ROD

S.S# S.P# S.QTY

4532

4534

4535

123

345

567

10

40

5

P# PNAME

4532

4534

4535

NUT

ROD

SCREEN


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8) SELECT COUNT ( * ) AS N FORM S;

Ans Count = N = 4

9) SELECT MAX ( S.QTY) AS MAXQ,

MIN (S.QTY) AS MINQ

FROM S

WHERE S. DISCOUNT = -1;

Answer MAXQ = 40

MINQ = 10

10) UPDATE Operations:

INSERT INTO P ( P#, PNMAE)

VALUES (4536, ‘STRING’);

?

Ans

DELETE FROM P WHERE P.PNAME = ‘ROD’;

P# PNAME

4532

4555

4535

4534

4536

NUT

BOLT

SCREEN

ROD

STRING

P# PNAME

4532

4555

4535

4536

NUT

BOLT

SCREEN

STRING

lecture by prof.dr.s.sridhar 1 database technology by dr.s.sridhar, ph.d.(jnud), raci(paris, nice),...

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