Computer knowledge

C# shape programming/Console program

2018-12-16T21:37:00.002+05:30

1.WRITE A CONSOLE PROGRAM PRIME OR NOT>

PROGRAM:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ConsoleApplication4

{

class Program

{

static void Main(string[] args)

{

int a, i, b = 0;

Console.WriteLine("Enter the number to check prime or not");

a = int.Parse(Console.ReadLine());

for (i = 2; i <= a / 2; i++)

{

if (a % i == 0)

{

Console.WriteLine("The number " + a + " is not prime");

b++;

break;

}

if (b == 0)

Console.WriteLine("The number " + a + " is prime number");

}

OUTPUT:

2.WRITE A CONSOLE PROGROM TO TRIM A STRING>

PROGRAM:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ConsoleApplication6

{

class Program

{

static void Main(string[] args)

{

string myString = " prasun ";

System.Console.WriteLine("The String Before Trimming : (" + myString + ")");

System.Console.WriteLine("The String After Trimming : (" + myString.Trim() + ")");

Console.Read();

}

OUTPUT:

3.WRITE A CONSOLE PROGRAM PERFECT SQUARE OR NOT>

PROGRAM:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace EvenOdd

{

class Program

{

static void Main(string[] args)

{

int num,sq;

Console.WriteLine("Enter a Number to Check a Number is Perfect Square or Not");

num = int.Parse(Console.ReadLine());

try

{

sq =int.Parse(Math.Sqrt(Convert.ToDouble(num.ToString())).ToString());

if (sq*sq==num)

Console.WriteLine("The number " + num + " is Perfect Square Number");

}

catch

{

Console.WriteLine("The number " + num + " is not Perfect Square Number");

}

OUTPUT:

4.WRITE A CONSOLE PROGRAM EVEN OR ODD>

PROGRAM

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ConsoleApplication4

{

class Program

{

static void Main(string[] args)

{

int n;

Console.WriteLine("Enter the number");

n = int.Parse(Console.ReadLine());

if (n % 2 == 0)

Console.WriteLine("The number " + n + " is an even number");

else

Console.WriteLine("The number " + n + " is an odd number");

}

OUTPUT :

5.WRITE A CONSOLE PROGRAM TO GENERATE THE SUM OF N NUMBER>

PROGRAM:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace b_to_d

{

class Program

{

static void Main(string[] args)

{

int i, sum = 0, n;

Console.Write("Enter the Nth Number : ");

n = int.Parse(Console.ReadLine());

for (i = 0; i <= n; i++)

{

sum = sum + i;

}

Console.WriteLine("\nSum of N Numbers : " + sum);

Console.ReadLine();

}

OUTPUT :

BEST BOOKS IN C &C++

2018-10-15T03:50:00.000+05:30

BEST BOOKS IN C:

BEST BOOKS IN C++:

Relational Algebra

2018-08-23T02:24:00.001+05:30

RELATIONAL ALGEBRA:

Relational algebra collection of operations generate new relations after manipulating one or more existing relation. It is a procedural language with operations. It consists of a set of relations operations.Each operator has one or more relations as its input and produces a relation as it's output.Thus the output from one operation can become the input to another operation. This allows expressions to be nested in the relational algebra. This property is called relation are closed under the algebra.

The operations are based on two groups of logical entities are called operators. One group consists of the traditional set operator namely----UNION,INTERSECTIONS,DIFFERENCES,CARTESIAN PRODUCT, and the other group contains special or native relational operational operators, namely-----SELECTION,PROJECTION,JOIN,and DIVISION.

►UNION:

The union operator is denoted by symbol "U" or"+", and it acts on two real items to generate a new relations containing all tuple of the relations accept the duplicate once.This implied that the new relations will have tuple which will belong to either the first relation or the second or both.Thus the result of those operation denoted by "R"U"S", is a relation that includes all tuple those are either in "R" or in "S" or in "R&S". Duplicate tuple are eliminated.

To perform union operation on two relations,both operand and relation must be union compatible,which means that they must have same no. of columns drown from the same domain,i.e, must be of same data type.

Example:

Let "R" and "S" be the two relations as-------------

Thus RUS yields------

►INTERSECTIONS:

The intersection operator is denoted by the word intersect or the symbol "ᴖ" and it acts on another relation consisting of only the common tuple between the two.The result of this operation denoted by RᴖS include all tuple that are in both "R" and "S".

Example:

Let "R" and "S" be the two relations as-------------

RᴖS yields-----

ID STUDENT NAME

1. RAM

►DIFFERENCE:

The difference operator is denoted by the symbol "-";

and it operator on two relations to yield a third relation that comprise all tuples belonging to the relations. a difference operator can be achieved.

►CARTESIAN PRODUCT:

The extended Cartesian product of two relations is denoted by the operator "X", and it product a third relation containing all possible tuple that may be formed by concatenation the attributes of the relation.

Example:

Let "R" and "S" be the two relations as-------------

RELATION R RELATION S

Then "RXS" yields------

What is Normalization?1NF,2NF,3NF,BCNF with Example

2018-08-08T18:18:00.000+05:30

NORMALIZATION:

Normalization is a scientific method of Breaking Down Complex table structure into simple table structure by using certain rule. We can, therefore, reuse redundancy in a table and eliminate the problem of inconsistency and disk usages. We can also ensure that there is no loss of information.

Normalization is a scientific method of Breaking Down Complex table structure into simple table structure by using certain rule. We can, therefore, reuse redundancy in a table and eliminate the problem of inconsistency and disk usages. We can also ensure that there is no loss of information.

Normalization result in the formation of table that certify certain specified rule and represent certain normal form. The normal from are used to ensure that various type of anomalies and inconsistency are not introduced in the database. A table structure is always certain normal form. Several Normal Form never been identified. The most important and wiedly use normal form are------
1.1NF(Fast normal form)
2.2NF(second normal form)
3.3NF(third normal form)
4.BCNF(Boyce-code normal form)

1.1NF(Fast normal form):

A table is said to be in the 1NF when each cell of the table contains precisely one value.

For example consider the following table student

In above table the data is not normalize because the cells in department and student name more then one value,by applying the 1NF definition to the project table, we arrive at the following table----

2.2NF(second normal form):

A table is said to be in 2NF when it is in 1NF and every attribute in the row is functionally dependent upon the hole key, and not just part of the key.

For example consider the following table project

In above table E-CODE+ PROJECT CODE is composite primary key. The table specify is the definition of the 1nf because each cell table content one value but for each value of E-CODE, there is more then on value of duration. Duration is not functionally dependent on E-CODE similarly for each value of PROJECT CODE, there is more than one value of duration. Hymns duration is not functional dependent on PROJECT CODE. However, for a combination of the E-CODE and PROJECT CODE value, there is exactly one value of the duration. Hence the attribute duration is functionally dependent on the hole key E-CODE+ PROJECT CODE. For each value of E-CODE, there is exactly one value of department. Themes department is the functional dependent on E-CODE which is also part of the composite primary key. Similarly for each value of project code, there is more than one value of department. Hence, department is not functionally dependent on their attribute project code. Department is also functionally dependent on the hole key because for each value of department there is exact on value on the combination E-CODE+ PROJECT CODE value. Hence the table is not into 2NF.

To convert the above table after applying 2NF rule on project table-----------

3.3NF(third normal form):
A table said to be 3NF when it is in 2NF and every non-key attribute is functionally dependent only on the primary key.

for example constant the following table employee

In above table E-CODE is primary key. For each value E-CODE, there is exact on value of department. Hence, the attribute department is functional dependent on the primary key E-CODE. Similarly, for each value E-CODE, there is example of Department Head.Hence, Department Head is fully functionally dependent on primary key E-CODE. Hence, all the attribute are functionally dependent on are hole key E-CODE,Hence the table is in 2NF.
However,the attribute Department Head if the dependent on the attribute department also. As per 3NF rule, all non key attribute have not to be functionally dependent only on the primary key.Hence this table is not in 3NF, Since Department Head is functionally dependent on department, which is not a primary key.

So we convert the above table after applying 3NF rule-----------

4.BCNF(Boyce-code normal form):
A relation is said to be BCNF if and only if every determine is a candidate key.

PROGRAM IN C

2018-08-06T22:26:00.000+05:30

1.WRITE A C PROGRAM TO CALCULATE SUM OF TWO NUMBERS

PROGRAM:

# include<studio.h>

#include<conio.h>

void main()
{

Int a,b,c;

printf(“Enter the two no to calculate sum :”);

scanf(“%d%d”,&a&b);

c=a+b;

printf(“The sum of %d and %d is =%d”,a,b,c);

getch();

}

OUT PUT :

Enter two number to calculate sum: 3 4

The sum of 3 and 4 is =12

2.WRITE A C PROGRAM TO CALCULATE TO CHECK A

NUMBER EVEN OR ODD

PROGRAM:

# include<studio.h>

#include<conio.h>

void main()
{

int n;

printf(“Enter the numbers to check even or odd :”);

scanf(“%d”,&n);

if(n%2==0)

printf(“Given numbers is even”);

else

printf(“Given numbers is not even”);

getch();

}

OUT PUT :

Enter the numbers to check even or odd : 11

Given numbers is not even

Enter the numbers to check even or odd: 10

Given numbers is even

3. WRITE A C PROGRAM TO CALCULATE MULTIPLICITE OF TWO NUMBER

PROGRAM:

#include<stdio.h>

#include<conio.h>

{

int a,b,c;

printf(“Enter two numbers to calculate multiplication :”);

scanf(“%d%d”,&a&b);

c=a*b;

printf(Multiplication=%d”,c);

getch();

}

OUT PUT:

Enter two numbers to calculate multiplication :4 5

Multiplication=20

4.WRITE A C PROGRAM TO DISPLAY YOUR NAME FIVE TIME IN

PROGRAM :

#include<stdio.h>

#include<conio.h>

void main()

{

int a;

printf(“My name 5 times in”);

while(i<=5)

{

printf(“RAM \n”);

i=i+1;

getch();

}

OUT PUT :

My name 5 time in

RAM

5.WRITE A C PROGRAM TO DISPLAY THE FOLLOWING

***

****

PROGRAM :

#include<stdio.h>

#include<conio.h>

void main()

{

int i=1;

clrscr();

printf(“In the required display is \n”);

while(i<=4)

{

j=1;

while(j<=i)

{

printf(“*\t”);

j++;

}

i++;

printf(“/n”);

}

getch();

}

OUT PUT :

In the required display is

***

****

6.WRITE A C PROGRAM TO DISPLAY ALL EVEN NO

BETWEEN A RANGE

PROGRAM :

#include<stdio.h>

#include<conio.h>

void main()

{

Int i,start,end;

clrscr();

printf(“Enter the range to display all even no. between a range\n”);

scanf(“%d%d”,&start,&end);

i=start;

printf(“All even no.between %d to %d are\n”,start,end);

while(i<=end)

{

if(i%2==0)

printf(“%6d”,i);

i++;

}

getch();

}

OUT PUT :

Enter the range to display all even no. between a range

All even no. between 1 to 10 are

2 4 6 8 10

7.WRITE A C PROGRAM TO DISPLAY ALL NUMBERS BETWEEN A RANGE

PROGRAM :

#include<stdio.h>

#include<conio.h>

void main()

{

int i,start,end;

printf(“Enter the range to display the no.\n”);

scanf(“%d%d”,&start,&end);

i=start;

printf(“All number between %d to %d are \n”,start,end);

while(i<=end)

{

printf(“%6d”,i);

i++;

}

getch();

}

OUT PUT :

Enter the range to display the no.

All number between 1 to 10 are

1 2 3 4 5 6 7 8 9 10

8.WRITE A C PROGRAM TO COUNT NUMBER OF

DIGIT OF A NUMBER

PROGRAM :

#include<stdio.h>

#include<coio.h>

void main()

{

int n,c=0,i,t;

printf(“Enter a no. to count the digit \n”);

scanf(“%d”,&n);

t=n;

while(t!=0)

{

c++;

t=t/10;

}

printf(“The no. %d is %d digits”,n,c);

getch();

}

OUTPUT :

Enter a no. to count a digit

123

The no. 123 is 3 digit

9.WRITE A C PROGRAM TO CHECK A NO IS PRIME OR

NOT

PROGRAM :

#include<stdio.h>

#include<conoio.h>

void main()

{

int n,i=2,f=0;

clescr();

printf(“Enter a no. to check prime or not \n”);

scanf(“%d”,&n);

while(i<=n/2)

{

if(n%i==0)

{

f++;

break;

}

i++;

}

if(f==0)

printf(“%d is a prime no.”,n);

else

printf(“%d is not a prime no.”,n)

getch();

}

OUTPUT :

Enter a no. to check prime or not

12 is a prime no.

Enter a no. to check prime or not

11 is not a prime no.

10.WRITE A C PROGRAM TO DISPLAY ALL PRIME NO.

UPTO n

PROGRAM :

#include<stdio.h>

#include<comio.h>

void main()

{

int n,i,f,j=0;

clrscr();

printf(“Enter a no. to find the all prime no.s\n”);

scanf(“%d”,&n);

printf(“All prime no.s up to %d”,n);

while(j<=n)

{

f=0;

i=2;

while(i<=j/2)

{

if(n%i==0)
{

f++;

break;

}

i++;

}

if(f==0)

printf(“%d\t”,j);

j++;

}

getch();

}

OUT PUT :

Enter a no. to find all prime no.

All prime no. up to 6

1 2 3

variable in c

2018-07-30T16:08:00.001+05:30

WHAT IS VARIABLE?

Just like a container; that can help to store data with specific type.

Example: int,char,string,

* In 'C' Language to declare a variable should maintain following point---------

➡️ 1st character should be an alpha or underscore(_).
Ex: number,_number
➡️ Do not use any special character except under score(_)
Ex: student@name⛒
student+name⛒
student_name✓
➡️ May or may not sure numeric digits
Ex: 1no⛒
_1no✓
no1✓
n1o✓
➡️ Upper case and lower char are distinct
Ex: no✓
No✓
NO✓
nO✓

* How to declare a variable?
syn: <datatype> <variable name>;

Ex: int a;
float b;
Type of Variable:
1. int a; (signed short integer)
2. unsigned int b; (unsigned short integer)
3. long c; (signed long integer)
4. unsigned long d; (unsigned long integer)
5. float p; (single precision real variable )
6. double r;(double precision real variable)
7. long double s;(double precision real variable)
8. char n;(character variable )
9. char name[30];(string variable)

Privacy policy

2018-07-28T15:31:00.000+05:30

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Constructor

2018-07-26T16:26:00.001+05:30

WHAT IS CONSTRUCTOR?

A constructor is a special member function whose task is to initialize the object of its class. It is special because its name is the same as the class name in which they define and automatically will be invoked when ever and associated class it created. It is called constructor class because it contract the value of data member of class.

constructor may be characterized by-------

1. Parameterized constructor :

A constructor that can take argument or parameter- called parameterized constructor. In case of parameterized constructor must pass the initial value as argument to the constructor function when an object is declared. This is done by one from following------

a.By calling the constructor explicitly-----

Example:

#include<iostream.h>

#include<conio.h>

class xyz

{

int num;

public;

xyz(int x)

{

num=x;

}

void display(void)

{

cout<<"\n number="<<num;

}

};

void main()

{

xyz a=xyz(100); //calling constructor explicitly.

clrscr();

a.display();

getch( );

}

b.By calling the constructor implicitly-----

Example:

#include<iostream.h>

#include<conio.h>

class xyz

{

int num;

public;

xyz(int x)

{

num=x;

}

void display(void)

{

cout<<"\n number="<<num;

}

};

void main()

{

xyz a(100); //calling constructor implicitly.

clrscr();

a.display();

getch( );

}

2. Non parameterized constructor :

A constructor that accept no parameter or argument is called non parameterized constructor or default constructor. In c++ if know such constructor is define then the constructor supplies is default constructor.

Example:

#include<iostream.h>

#include<conio.h>

class xyz

{

int num;

public;

xyz(void)

{

num=100;

}

void display(void)

{

cout<<"\n number="<<num;

}

};

void main()

{

xyz a; //calling constructor implicitly.

clrscr();

a.display();

getch( );

}

Basic characteristic of constructor:

The basic characteristic of constructor are------

1. The name of the should be same as the class name in which they declared.

2. They should be declared in the public sector of class.

3. They do not return type,not even void and there for they cannot return value.

4. May or may not be parameterized.

5. In case of parameterized constructor they can have default argument.

6. Constructor can be overloaded.

7. Constructor can be virtual.

8. Cannot refer address of constructor.

scheduling

2018-07-19T18:10:00.000+05:30

WHAT IS CPU SCHEDULING?

Scheduling refers to the set of policies and mechanisms that an OS support for determining the order of execution of the pending jobs and processes.

WHAT ARE THE OBJECTIVE OF CPU SCHEDULING?

1. Fairness:
Makes sure each process get it's fair of CPU.

  2. Efficiency:
Keep the CPU busy hundred percent so that efficiency is increased.

  3. Response time:
Minimize the response time.

  4. Through put:
Minimize the through put.

  5. CPU Utilization:
The CPU utilization specially on the time shared system should be maximum.

WHAT IS SCHEDULER?

When more than one process is runable,the OS must decide which one to be run fast. The part of the OS concerned with the decision is called scheduler, and the algorithm it uses is called the scheduling algorithm.

TYPE OF SCHEDULER:

1. L.T.S (Long Term Scheduler)

2. M.T.S(Middle Term Scheduler)

3. S.T.S(Short Term Scheduler)

1. L.T.S (Long Term Scheduler):

The long term scheduler is also called the job scheduler. This scheduler determines which jobs are admitted to the system for processing. It is also called admission scheduler, because it determines which job gains admission to the system.

In batch processing system more jobs are spooled to a mass storage device. The Long Term Scheduler select these job from job pools and loads these into memory for execution.

2. M.T.S(Middle Term Scheduler):

many time we need to remove a process from the main memory as this process maybe in need of some input output operation. So such processes may be removed or suspended from the main memory to the hard disk. Letter on this process can be reloaded into memory and continued from from it was left earlier. This saving of the suspended process is said to be swaped out or rolled out and this swapping is done by medium term scheduler.

It acts as the intermediate between LTS and STS.

3. S.T.S(Short Term Scheduler) :

This scheduler is sometime called CPU scheduling, or CPU scheduler. The short term scheduler selects among the job in memory, which are ready to execute and allocate the CPU to one of them. It's main objective is to maximum CPU utilization.

Inheritance

2018-07-14T00:04:00.001+05:30

What is inheritance?

The mechanism by which a new class in derived from existing classes is called inheritance. Here existing classes are known as discussed and the new classes are known as derived classes.

By following figure we can demonstrate the basic concept of inheritance--------

Fig: basic concept of inheritance

Characteristic of inheritance:
In C++ inheritance machanism is may be categorise by--------
1. Single inheritance
2. Multiple inheritance
3. Multilevel inheritance
4. Hierarchical inheritance
5. Hybrid inheritance
6. Multipath inheritance

1. Single inheritance:
The inheritance mechanism in which a new class we derived from only one base class is called single inheritance.

2. Multiple inheritance:
the inheritance mechanism in which a new classes is derived from two or more base classes then it is termed as multiple inheritance.

3. Multilevel inheritance:
The inheritance mechanism in which a new class is derived from another derived class called multilevel inheritance.

4. Hierarchical inheritance:
The inheritance mechanism in which two or more new class are derived from only one base class then it is term as hierarchical inheritance.

5. Hybrid inheritance:
The inheritance mechanism in which two or more inheritance concept are applied then it is termed as hybrid inheritance.

6. Multipath inheritance:
When the child has two direct base classes which themself have a common base class then the child inheritance the treated of grandparent vai to separate path. This type of inheritance is referred to as multipath inheritance their child class would have duplicate set of the member inheritance from grandparents thought parent classes.

Oop,pop

2018-07-09T00:25:00.000+05:30

What is oop?

Object oriented programming is an approach that provide a way of modelling program by creating partition memory area for both data and function that can be used as as templates for creating copies officers modulus on demand.

The major features of oop are----

1. Emphasis is on data rather than prosedure.

2. Follows bottom up programming approach.

3. Data is hiding and cannot be accessed by external function (data encapsulation).

4. Program are divided into object.

5. Object may communicate with each other thought function.

6. Automatic initialisation of object.

7. Automatic clear up of object.

8. Polymorphism.

9. Inheritance.

10. Templates.

What is pop?

Procedure oriented programming basically consists of write a list of instruction for the computer of follow, and organising these instruction into group known as function. Generally flow chat is used to organises this action of procidure oriented program.

The major features of pop are----

1. Emphasis is on procidure.( Algorithm rather then data).

2. Follows top down programming approach.

3. Large program divided into small program, known as function.

4. Data move openly around the system from one function to another.

5. Most of the function share global data.

6. Function transfer data from one form to another.

contact us

2018-07-05T14:16:00.003+05:30

C

2018-07-04T18:10:00.000+05:30

C:
✓ High level programming language.

✓ But also support the concept of features of low level language. Hence 'C' is also called a High level language.

✓ Developed by Denis Ritche at AT &T Bell's Lab,USA in 1972.

What is C?

C is a high level language developed by Denis Ritche at AT &T Bell's Lab,USA in 1972. C is also called higg level language.

Basic characteristics of c program:

1. Program should be written in small latter, except some special cases.
2. Should use are main() function with in a program.
3. ShiSho use semicolon (;) at the end of evhe statement.
4. Should include specific Hader file by #include directive as per needs the program.
5. Should be declared/define work variables with proper data type.

C++

2018-07-03T16:46:00.001+05:30

C++
✓ Object oriented programming language.
✓ Superset of 'c'
✓ Developed by- Bjarne Stroustrup at Bell Labs since 1979
✓ Support the concept of INHERITANCE
✓ Support the concept of POLYMORPHISM
✓ Support the concept of BOTTOM-UP-PROGRAMMING APPROACH.

WHAT IS C++?

C++ is a object oriented programming language developed by Bjarne Stroustrup at Bell Labs since 1979,USA,in the early 80's has a superset of C language.

The three important that C++ add on to C are----

1. Classes

2. Function overloading

3. Operator overloading

These futures enable us abstract data type , inherit propatisb from existing data type and support polymorphism.

What is the features in c++??

The object oriented features in c++ allows programmer -------

1. To build the large program with clearity.

2. Extrnbility.

3. Easy of maintained, Incorporating the spirit and efficient of C.

What is the major characteristic in c++??

The major characteristic of C++ are------

1. Emphasis is on data rather than procedure.

2. Data structure are designe such that they characteristic they object.

3. Program are devided into object.

4. Data is hiden an can not be access by extranal function.

5. Object may communicate with each other thought function.

6. New data and function can be easily added when ever necessary.

7. Follow bottom-up-appoch in program design.

Key

2018-06-30T18:04:00.000+05:30

What is key?

A key is a set of one or more columns whose combine values are unique among all occurrences in a given table.

Key may be characterized by-------

1. Unique key

2. Candidate key

3. Primary key

4. Composite primary key

5. Alternate key

6. Foreign key

7. Super key

1. Unique key:

Unique key is a set of one or more column to identify the uniquely in the database.

Unique key also provide one null value, but unique key cannot provide duplicate entry like as primary key.

2. Candidate key:

An attribute that uniquely identify a row is called candidate key.

Candidate key also known as surrogate key.

For example, in the STUDENT (Registration_no,Class,Section,Roll_no) table

Registration_no,Roll_no are the candidate key.

3. Primary key:

A candidate key which is used to identify a row uniquely is called primary key. Primary key cannot provide duplicate entry.

For example,in the STUDENT(Registration_no,Class,Section,Roll_no) table Registration_no is a primary key.

4. Composite primary key:

When the key that uniquely identify the row of the table is made up more than one attribute then it is called composite primary key or CPK.

For example, in the STUDENT (Registration_no,Class,Section,Roll_no) table

Class,Section,Roll_no are the composite primary key.

5. Alternate key:

If there are multiple candidate can in a table, the candidate keys that are not chosen as primary key will be called alternate key.

For example, in the STUDENT (Registration_no,Class,Section,Roll_no) table

Roll_no is a alternate key.

6. Foreign key:

When a primary key of one table is also available as another attribute in another related table then it is called foreign key.

For example, in the STUDENT (Registration_no, Class,Section,Roll_no)table

Registration_no is primary key and the EXAM(Registration_no,sub1,sub2,sub3,Roll_no) table Roll_no is primary key. The primary key registration_no of STUDENT table is also available in EXAM table. Hence registration_no of EXAM table is foreign key of STUDENT table.

7. Super key:

A super key for an entity set is a set of one or more attributes, whose combined values uniquely identifies the entities.

For example, in the STUDENT (Registration_no,Class,Section,Roll_no, Address) table Address is super key.

Threads

2018-06-28T00:22:00.000+05:30

What is threads?

Generally a process consists of number of lightweight process. These lightweight process basically called thread. Actually a threads is a single sequential flow of control within a program. It has a beginning,an end, a sequence etc. But a thread it self is not a program because it cannot run on it's own, it runs with in a program, and thus it makes use of the resources that were actually allocated to the process.

The thread has a program counter that keeps the tracks of which instruction to execute next, it has registers, which hold its current working variables. It has a stack which contains the history of execution. Threads can execute anywhere in the code space of the process.

Uses of threads:
A typical use of threads is found in servee application, such as database server.

Advantage of threads:

Basic function of threads:

Threads can perform many of the functions of process --------

1. Threads allows parallelism to combined with sequential execution and block system calls.

2. Threads are frequently used for client.
3. Threads can also be organised in the pipeline model.

Classification of threads:

There are two ways of thread implementation, they are as follows------

a. User level threads
b. Kernel level threads

a. User level threads:
These type of threads are loaded in the user space only. When Threads are managed in the user space, each process must have its own private thread tables. This pivot table consist of the information of the program counter, stack pointer, register etc, and is managed by runtime system.
By following figure we and demostate the basic concept of user level threads----

Fig: user level threads

Advantages of user level threads:

1. Each process can have its own scheduling algorithm.

2. User level thread can run on any OS.

3. Faster switching among thread is possible.

Disadvantages of user level threads:

1. When a user level thread execute a system call, not only that thread is blocked but also all of the chat within the process are blocked.

2. Multithreaded application using user level threads cannot take the advantages of multiprocessing sinces kernel assign one process to only one processor at a time.

Kernel level threads:

In this method of thread implementation, the kernel does Total Work of threads movement. There is no thread table in each process. The kernel has a thread table which keeps track of all the threads in a system . The kernel's thread table holds each thread registers, state and other information. Using kernel only, a thread can create a new threads and destroy an existing threads.

By following figure we can demonstrate the basic concept of kernel level thread------

Fig: kernel level threads

Advantages of kernel level threads:

1. It supports multiprocessing also. It means that the kernel can simultaneously scheduling multiple Threads from the same process on multiple processors.

2. Karnal routines them selves can be multithreaded.

3. If a thread within a process is blocked, then the Karnal can schedule another thread of the same process.

Disadvantages of kernel level threads:

1. Switching between thread is time consuming because the kernel mast do the switching.

2. Creation and destruction of the threads in the kernel is costlier.

What is multithreading?

A process is divided into the smaller tasks and the each task is called as a thread. The use of multithreads in a single program, all running at the same time and performing different tasks is called multithreading.

For example, JAVA browser is a multithreaded application.

Advantage of multithreading:

On single processor machines, multithreading have several advantages------

1. Some task take much longer to execute then another.

2. Some task need a better deterministic outcome then other.

3. Some user interface activities is to be run concurrently with hardware communication.

Process control block

2018-06-27T18:03:00.001+05:30

What is process control block (PCB)?

When a user initiates of a new process, the OS collect all the information that is need about that particular process into a data structure called as a process control block (PCB) or task control block.

It act repository for any information for process. PCB is implemented as a record containing vital information like process state scheduling information, access control information etc. Show in the following figure------

Fig: process control block

What is parent process and child process?

The process creating a new process is called parent process.

If a process p1 can create another process p2, then p2 is called child process of parent process p1.

What is context switch?

It is a typical of interrupt handler. Context means the state, i.e., state of the process. Switching means switch from one process to another process.

When an interrupt occur, the primary work is does, is to save the context of the current process. Saving a process is called half context switch. The other half of the context switch is the restoring of the context of the next process to run. The saving and restoring is called a full context switch.

Attribute

2018-06-25T23:47:00.001+05:30

What is attribute?

It is a properties of an entity type. Is entity with normally have one or more attribute. It may be thought of the smaller pieces of information with in an entity.

Attribute may be categorised by-------

a. Simple attribute

b. Composite attribute

c. Single valued attribute

d. Multivalued attribute

e. Derived attribute

a. Simple attribute:

Attribute that could not be derived into subpart called simple attribute.

For example, 'student_id','reg._no','employee_id' etc.

b.Composite attribute:

Attribute that could be derived into subpart that are way of hierarchical organising attribute called composite attribute.

For example, 'Name' is a composite attribute because it can be derived first-name, middle-name, last-name.

c. Single valued attribute:

An attribute can take only one value for a given instance called single valued attribute.

For example, 'roll-number' is a single valued attribute.

d. Multivalued attribute:

An attribute may take more than one value of the given entity instance.

For example,'phone_no' attribute for specific entity set may have more than one number.

e. Derived attribute:

An attribute whose value can be calculated from the related attribute values called derived attribute.

For example, 'age' attribute can be derived from the date of birth attribute and so they are related.

Entity

2018-06-25T19:46:00.000+05:30

What is entity?

An entity is an object with a physical existence or it may be conceptual, so every organisation have some item or event of interest is called entity. It is described in a database a set of attribute. Every attribute is connected to one and only one entity.

For example, Student,Employee etc. are the entity.

Entity set are of two type---

a. Independent entity

b. Dependent entity

An independent entity is one that does not rely on another for identification.

A dependent entity is one that relies on another for identification.

What is entity set?

A group of similar object about which data are maintained in an organisation is called entity set, i.e., it is defined as a set of entities what are same type that share the same properties of attribute.

Entity set are of two type-------

a. Strong entity set

b. Weak entity set

a. Strong entity set:

An entity set that has a primary key is called a strong entity set. A strong entity is identify uniquely by consider primary key or composite primary key.

b.Week entity set:

An entity can be identified only by considering the primary key of owner entity called Weak entity.

Architecture of DBMS

2018-06-23T16:01:00.000+05:30

Explain the architecture of DBMS or three schema architecture?

In this architecture schema can we define at the following three level-----

1. Internal level
2. Conceptual level
3. External level or view level

1. Internal level:

The internal view is at the lowest level of the database abstraction. It is the one closest to the physical storage, i.e, in this level, the data is actually Store. The internal level has an internal schema use a physical data model and describe the complete details of data storage and access path for the database. It indicates how the data will be store and describe the data structure that could be used by the database.

2. Conceptual level:

The conceptual level have a conceptual schema, which describe the structure of the hole database for a community of user. The conceptual schema hides the details of the physical storage structure and consented on describing entities, data type, relationship, user operation and constants. A high level data model or implementation data model can be used at this level.

3. External level or View level:

The external or user view is at the highest level of the database abstraction. It is a view level and includes a number of the user's views. Each external schema describe the part of the database, that a particular user group is interested in and hides the rest of the database from the user group.

By following figure we can demonstrate at the basic concept of the three schema architecture or architecture of DBMS---------

Fig: Three schema architecture or architecture of DBMS

Data Independence

2018-06-23T15:26:00.000+05:30

Data Independence:

The ability to modify the conceptual schema without having changes the external schema or application program, or to modify the internal schema without having changes the conceptual schema .

Data Independence may be categorised by-----

1. Logical data independence:

The ability to modify(change) the conceptual schema without having changes external schema or application program we may be changed the conceptual schema to explain the database( by adding a new record type or data item), or to reduce the database (by removing a record type or data item).

2. Physical data independence:

The ability to modify(change) the physical schema without having changes the conceptual schema. Change to the internal schema may be needed because some physical file add to be recognised.

Schema

2018-06-23T15:05:00.001+05:30

What is schema?

The logical structure of the database is called schema.

Schema may be categorised by------
1. Physical schema:-
Database design at physical level.
2. Logical schema:-
Database design that logical level.

What is instance?

The actual content of the database at a particular point in time called instance. It is a analogous to the value of variable.

Three schema architecture or architecture of DBMS?

http://comknowledge1.blogspot.com/2018/06/architecture-of-dbms.html?m=1

About us

2018-06-22T17:58:00.000+05:30

Founded on june 19, 2018, in Medinipur City, paschim Medinipur, by PRASUN KHANRA,Computer knowledge free any computer related education and information to everyone.

Today, Computer knowledge continues to provide free support and computer education that allow any user to learn more about their computer and find technical assistance. Some of the services we offer include free help, information, tips, any computer related questions & answers are available.

Our View

We hope to make Computer knowledge the number one destination for computer support while also helping everyone get the most from their computer.

Website Goals

1. Easy education of computer subject.

2. Help of all viewer.

3. Easy answer are available.

History

June 19,2018 component knowledge is released to published.

DBMS

2018-06-22T16:56:00.000+05:30

WHAT IS DATA?

Data is a collection of raw facts.

WHAT IS DATA BASE?

A database is well-design collection of related data. By data we mean known fact that can be followed a particular architecture and the architecture should support and efficient data storage and retrieval mechanism.

For example, consider the names, telephone numbers and address of the people we know. We may have record this data in an index address book or we may have store it on a disk, using a personal computer. These is a collection of related data with an implicit meaning and hence it is database.

Example:

(a) telephone directory

(b) Dictionary

WHAT IS DBMS?

A database management system (DBMS) is a collection of programs that enable user to create and maintain a database. The DBMS is a general purpose software system the facilities of process of defineing, constructing and manipulating database for various applications.

Defineing a database involve spacifying the data type, structures and constants constant for the data to be store in the database.

Manipulating a database includes such function as querying the database to retrieve reports form the data.

By following figure we can demonstrate the basic concept of DBMS-----

Fig: simplified database system environment illustrating the concept and terminology

Advantages of DBMS:

1. Data can be easily share.

2. Redundancy can be reduced.

3. Inconsistency can be avoided to some content.

4. Transaction support can be provide.

5. Integrity can be maintenance.

6. Fixable.

7. Always up to date data information available.

Disadvantages of DBMS:

1. High initial investment in hardware software and training.

2. Overhead for providing security.

3. Periodical maintenance is too high due to hardware and software upgradation and staff training.

Process management

2018-06-21T13:22:00.000+05:30

WHAT IS PROCESS?

A process is an instance of a program in execution. In other word process is an asynchronous piece of computation. The span of time of process is limited.

PROCESS STATES:

There ate four different states are -------

1. Runing state:

A CPU is currently allocate of the process and the process in execution.

2. Block state:

A process is said to be blocked if it is waiting for some event before it can proced. Such as a Process cannot be execute even if a CPU available.

3. Ready state:

The process is not running however it can execute if a CPU is allocated to yet. That is the process is not blocked.

4. Terminated state:

The the process has finished in execution.

WHAT IS PROCESS STATE TRANSITION?

When a job admitted to the system a corresponding process is created and then inserted at the block of the ready list. Now the process are in blocked state. Process are gradually moved towards the head of the ready list, and when CPU becomes available the frist forces of the ready list is assigned to the CPU. That is the process arrived at the running state from the ready state---- this is called state transaction.

By following figure we can demonstrate the basic concept of states transition----

Fig: process state transition