Subqueries allow queries to be nested within other queries. The inner, or subquery, is executed independently and its results are used by the outer query. Subqueries can be used with operators like =, <, >, etc. and SQL statements like SELECT, INSERT, UPDATE, and DELETE. Examples show how to find the maximum salary from an employee table and the name of the employee with the maximum salary using a subquery. Other examples demonstrate how to find employee names matching other criteria using subqueries.

1. SUB QUERIES
-VARSHA KUMARI

2. Sub Queries
 In nested queries, a query is written inside a query.
 The result of inner query(sub query) is used in
execution of outer query(main query).
 Subqueries can be used with the SELECT,
INSERT, UPDATE, and DELETE statements along
with the operators like =, <, >, >=, <=, IN,
BETWEEN, etc.

3. syntax
 SELECT column1,column2,..
FROM table1 [, table2 ]
WHERE column_name OPERATOR
(SELECT column FROM table1 [, table2
] [WHERE])
[ ] bracket means it is optional

4. Example – employee_table
E_id E_name Dept Salary
1 Ram HR 10000
2 Amit MRKT 20000
3 Ravi HR 30000
4 Nitin MRKT 40000
5 Hardik IT 50000

5. query
 Display the maximum salary from employee_ table
 Select max(salary) from employee_ table
 Display the name of employee having maximum
salary from employee_ table
 Select Ename from employee_ table where salary =
(Select max(salary) from employee_ table)

6. 

= 50000 false
= 50000 false
= 50000 false
= 50000 false
= 50000 True

7. Example :

8. Table creation

9.  Q. Find the name of the employees whose salary is
equal to salary of Arjun & Harthik?

10. SQL :
 select Emp_name from emp2 where salary
 IN
 (select salary from emp2 where Emp_name in
('Arjun', 'Harthik'));

11.  Q. Find the name of the employees whose belongs
to new york?


12. SQL
 select emp_name from emp2 where deptno
 IN
 (select deptno from dept where loc = 'NEW
YORK');

13.  Q. Find the name of the employees whose does not
belongs to ‘london’?

14.  select emp_name from emp2 where deptno
 NOT IN
 (select deptno from dept where loc
= 'LONDON');

15.  Q. Find the name of the employee who gets salary
greater than the average salary?

16.  select emp_name,salary from emp2 where salary
 >
 (select round(avg(salary),2) from emp2);

17.  Q. Find the department name and location of the
employee whose name is Aman?

18.  select dname,loc from dept where deptno =
 (select deptno from emp2 where emp_name =
'Aman');

19.  Q. Display all employee names and salary whose
salary is greater than minimum salary of the
company and job title starts with ‘D‘.

20.  Select Emp_name, Salary from emp2 where
Salary>(select min(Salary) from emp2 where job
like 'D%');

21.  Q write a query to find all the employees who
work in the same job as Arjun.

22.  Select Emp_name from emp2 where Job = (select
Job from emp2 where Emp_name='Aman');

23.  Issue a query to display information about
employees who earn more than any employee in
dept 1

24.  Select * from emp where Salary>(select
max(Salary) from emp where Emp_no=1);

25. Question
 Q. Write a query to display the name of employee
having 2nd maximum salary.
 Q. Write a query to display the name of employee
having 2nd minimum salary.
 Q. Write a query to display the name of employee
having salary less than the average salary.