EMPLOYEE TABLE in ORACLE (RDBMS)

Q.EMPLOYEE TABLE

create table EMP(eid number, ename varchar2(20),age number,salary number,company varchar2(60));

insert into EMP values (1,'raju',30,30000,'TCS');

insert into EMP values (2,'indu',35,40000,'IBM');

insert into EMP values (3,'kalia',40,50000,'CTS');

select *

from EMP;

drop table EMP;

select * 

from EMP

where company='TCS';

select ename 

from EMP

where salary>=40000;

select ename 

from EMP

where age<=35 and salary>=40000;

select ename 

from EMP

where age<=35 or salary>=40000;

select min(salary)

from EMP;

select min(salary) as minimum_salary

from EMP;

select max(salary)

from EMP;

select max(salary) as maximum_salary

from EMP;

select avg(salary)

from EMP;

select avg(salary) as average_salary

from EMP;

++++++++++++++++++++++++++++++++++++++++++++++++++++++++

create table EMP(eid number, ename varchar2(20),age number,salary number,company varchar2(60));

insert into EMP values (1,'raju',30,30000,'TCS');

insert into EMP values (2,'indu',35,40000,'IBM');

insert into EMP values (3,'kalia',40,50000,'CTS');

select *

from EMP;

drop table EMP;

select * 

from EMP

where company='TCS';

select ename 

from EMP

where salary>=40000;

select ename 

from EMP

where age<=35 and salary>=40000;

select ename 

from EMP

where age<=35 or salary>=40000;

select min(salary)

from EMP;

select min(salary) as minimum_salary

from EMP;

select max(salary)

from EMP;

select max(salary) as maximum_salary

from EMP;

select avg(salary)

from EMP;

select avg(salary) as average_salary

from EMP;

select ename

from EMP

where salary=(select max(salary)

                from EMP);

select ename

from EMP

where salary=(select min(salary)

                from EMP);

select ename

from EMP

where salary>=(select avg(salary)

                from EMP);

select ename

from EMP

where age=(select max(age)

                from EMP);

select ename

from EMP

where salary>(select salary

                from EMP

                where ename='raju');

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

update EMP set company='TCS'

where eid=1;

select * from EMP;

update EMP set company='IBM'

where eid=2;

select * from EMP;

update EMP set company='CTS'

where eid=3;

select * from EMP;

update EMP set age=age+1;

select * from EMP;

OS-Shortest Job First-SJF Scheduling

 #include<stdio.h>

int main()

{

    int bt[20],p[20],wt[20],tat[20],i,j,n,total=0,totalT=0,pos,temp;

    float avg_wt,avg_tat;

    printf("Enter number of process:");

    scanf("%d",&n);

 

    printf("\nEnter Burst Time:\n");

    for(i=0;i<n;i++)

    {

        printf("p%d:",i+1);

        scanf("%d",&bt[i]);

        p[i]=i+1;

    }

 

    //sorting of burst times

    for(i=0;i<n;i++)

    {

        pos=i;

        for(j=i+1;j<n;j++)

        {

            if(bt[j]<bt[pos])

                pos=j;

        }

 

        temp=bt[i];

        bt[i]=bt[pos];

        bt[pos]=temp;

 

        temp=p[i];

        p[i]=p[pos];

        p[pos]=temp;

    }

 

    wt[0]=0;

 

    //finding the waiting time of all the processes

    for(i=1;i<n;i++)

    {

        wt[i]=0;

        for(j=0;j<i;j++)

             //individual WT by adding BT of all previous completed processes

            wt[i]+=bt[j];

 

        //total waiting time

        total+=wt[i];   

    }

 

    //average waiting time

    avg_wt=(float)total/n;  

 

    printf("\nProcess\t Burst Time \tWaiting Time\tTurnaround Time");

    for(i=0;i<n;i++)

    {

        //turnaround time of individual processes

        tat[i]=bt[i]+wt[i]; 

 

        //total turnaround time

        totalT+=tat[i];      

        printf("\np%d\t\t %d\t\t %d\t\t\t%d",p[i],bt[i],wt[i],tat[i]);

    }

 

    //average turnaround time

    avg_tat=(float)totalT/n;     

    printf("\n\nAverage Waiting Time=%f",avg_wt);

    printf("\nAverage Turnaround Time=%f",avg_tat);

}

OS- First Come First Serve - FCFS Scheduling

 #include <stdio.h>

int main()

{

    int pid[15];

    int bt[15];

    int n,i;

    printf("Enter the number of processes: ");

    scanf("%d",&n);

 

    printf("Enter process id of all the processes: ");

    for(i=0;i<n;i++)

    {

        scanf("%d",&pid[i]);

    }

 

    printf("Enter burst time of all the processes: ");

    for( i=0;i<n;i++)

    {

        scanf("%d",&bt[i]);

    }

 

    int wt[n];

    wt[0]=0;

 

    //for calculating waiting time of each process

    for(i=1; i<n; i++)

    {

        wt[i]= bt[i-1]+ wt[i-1];

    }

 

    printf("Process ID     Burst Time     Waiting Time     TurnAround Time\n");

    float twt=0.0;

    float tat= 0.0;

    for(i=0; i<n; i++)

    {

        printf("%d\t\t", pid[i]);

        printf("%d\t\t", bt[i]);

        printf("%d\t\t", wt[i]);

 

        //calculating and printing turnaround time of each process

        printf("%d\t\t", bt[i]+wt[i]);

        printf("\n");

 

        //for calculating total waiting time

        twt += wt[i];

 

        //for calculating total turnaround time

        tat += (wt[i]+bt[i]);

    }

    float att,awt;

 

    //for calculating average waiting time

    awt = twt/n;

 

    //for calculating average turnaround time

    att = tat/n;

    printf("Avg. waiting time= %f\n",awt);

    printf("Avg. turnaround time= %f",att);

}

Program run command in Linux(Ubuntu)

 For Cpp

Create- gedit filename.cpp

Compile- g++ filename.cpp

Run- ./a.out

For C

Create- gedit filename.c

Compile- gcc filename.c

Run- ./a.out

For Java

Create- gedit filename.java

Compile- javac filename.java

Run- java filename

For python

Create- gedit filename.py

python3 filename.py  //only interpreter is used in python

Infix to prefix conversion

 ALGORITHM:

STEP 1:

Add " ( " at the beginning of the infix expression and then reverse.

STEP 2:

Push " ) " on to the stack.

STEP 3:

Scan every character and repeat step 4 to step 7 until " ( " is encountered.

STEP 4:

If input is operand add in the output.

STEP 5:

If input is " ) " push into the stack.

STEP 6:

If input is "(" pop all the operators from the stack and add in the output one by one until ")" is popped.

STEP 7:

If input is operator pop all the stack which is higher precedence than input operator .Push input operator into the stack.

STEP 8:

Reverse the output

EXAMPLE:

Infix to postfix conversion

 Step 1: Add " ) " to the end of the infix expression 

Step 2: Push " ( " on to the stack 

Step 3: Repeat until each character in the infix notation is scanned 

            - IF a " ( " is encountered, push it on the stack IF an operand (whether a digit or a character) is                      encountered, add it postfix expression. 

            - IF a " ) " is encountered, then 

                       a. Repeatedly pop from stack and add it to the postfix expression until a " ( " is                                             encountered. 

                       b. Discard the " ( " . That is, remove the " ( " from stack and do not add it to the postfix                              expression. 

           - IF an operator is encountered, then 

                      a. Repeatedly pop from stack and add each operator (popped from the stack) to the postfix expression which has the same precedence or a higher precedence than  0 .

                      b. Push the operator to the stack [END OF IF] 

Step 4: Repeatedly pop from the stack and add it to the postfix expression until the stack is empty 

Step 5: EXIT

Linked list push-pop

 #include<stdio.h>

#include<stdlib.h>

struct node {

    int data;

    struct node* link;

};

struct node* top = NULL;

void push() {

    struct node* temp = (struct node*) malloc(sizeof(struct node));

    printf("Enter a value: ");

    scanf("%d", &temp->data);

    temp->link = top;

    top = temp;

}

void pop() {

    if (top == NULL) {

        printf("Stack underflow\n");

    } else {

        struct node* temp = top;

        top = top->link;

        printf("Popped value = %d\n", temp->data);

        free(temp);

    }

}

void display() {

    if (top == NULL) {

        printf("Empty stack\n");

    } else {

        struct node* temp = top;

        while (temp != NULL) {

            printf("%d ", temp->data);

            temp = temp->link;

        }

        printf("\n");

    }

}

int main() {

    int choice;

    while (1) {

        printf("Enter 1 for push\n");

        printf("Enter 2 for pop\n");

        printf("Enter 3 for display\n");

        printf("Enter 4 for exit\n");

        printf("Enter your choice: ");

        scanf("%d", &choice);

        switch (choice) {

            case 1:

                push();

                break;

            case 2:

                pop();

                break;

            case 3:

                display();

                break;

            case 4:

                printf("Exiting the program\n");

                exit(0);

            default:

                printf("Wrong choice\n");

        }

    }

    return 0;

}