SQL

Question 1

How to select salary and add 300?

Answer 1

select salary, firstname, salary+300 from employees;

Question 2

Use aliases for select firstname and say name

Answer 2

select first_name as FirstName from Employees;

Question 3

Use aliases for select firstname and say name

Answer 3

select first_name as FirstName from Employees;

Question 4

Concatenate firstname and lastname and alias as full name

Answer 4

select firstname||lastname as fullname from employees;

Question 5

Get this output for me:
"Nilima is a programmer"
and nilima = firstname
job = programmer
with alias

Answer 5

select firstname ||’is a ‘|| job as employee_details from employees;

Question 6

Use q operator and write down “yea”

Answer 6

select firstname|| q’{yea] || managers as “Managers” from employees;

Question 7

Display all rows from employees

Answer 7

select department_id * from employees;

Question 8

Display unique elements

Answer 8

select DISTINT department_id from employees;

Question 9

What does Describe do?

Answer 9

Displays the structure of a table

Question 10

Select from employees where last_name is nilima.

and avoid that common mistake

Answer 10

select last_name
from employees
where
last_name=”nilima”;

Question 11

Select from employees where salary is less than 300, more than 300, between 200-800

Answer 11

select salary from employees
where salary BETWEEN 200 AND 800;
select salary from employees where salary <=300;

Question 12

Select names that begin with like “anychari”

Answer 12

select firstname from employees where firstname like ‘_i%’;

Question 13

How to find null manager id from employees?

Answer 13

select manager_id from employees where manager_id IS NULL;

Question 14

select from employees where salary is greater than 1000 and job_id is has the word “man” so IT_MAN

Answer 14

select manager_id from employees where
salary>=1000
AND
job_id LIKE ‘%MAN%’;

Question 15

select from employees where salary is greater than 1000 or job_id is has the word “man” so IT_MAN

Answer 15

select manager_id from employees where
salary>=1000
or
job_id LIKE ‘%MAN%’;

Question 16

What is the rule of precedence AND, OR and NOT

Answer 16

NOT
AND
OR

Question 17

how to sort in descending order

Answer 17

select firstname from employees

ORDER By date desc;

Question 18

Name function that changes to upper, lower and initcap

Answer 18

UPPER(“nilima”); NILIMA
LOWER(“manandhar”); manandhar
INITCAP(“nilima maandhar”);
Nilima Manandhar

Question 19

Use lower in sql query

Answer 19

Select last_name from employees where LOWER(first_name) = ‘manandhar’;

Question 20

How do you concat string?

Answer 20

CONCAT(‘hello’, ‘world’);

Question 21

How to find length,
I have Hello World.
I want only Hello
get rid of h from hellow

Answer 21

LENGTH(‘HELLOWORLD’);
SUBSTR(‘HELLOWORLD’, 1 ,5);
TRIM(‘H’ from ‘hellow’)

Question 22

What is the default date?

Answer 22

dd-MON-YY

Question 23

What does sysdate return?

Answer 23

it returns date and time
select sysdate
from dual;

Question 24

how to convert character, numbers and date?

Answer 24

to_char
to_date
to_number

Question 25

Name group functions

Answer 25

AVG, count, max, min, sum

Question 26

when do you use group by?

Answer 26

if you have group functions and select department_id then department_id should be group by select avg(salary) from employees group by department_id;

Question 27

``` Can you use where like this where AVG(salary)>300; ```

Answer 27

No that's why you use having? | Having(salary)>=300;

Question 28

What is a natural join?

Answer 28

it is based on all columns in the two tables that have the same name. It selects rows from the two tables that have equal values in all matched columns