1. Aggregate functions
Objective- understand and able to use aggregate functions in select statement
Aggregate functions are used to implement calculation based upon a particular column.
These functions always return a single value.

2. Aggregate functions function purpose Sum()
To find the sum of values of an attribute
Avg()
To find the average of values of an attribute
Max()
To find the highest values of an attribute
Min()
To find the lowest value of an attribute
Count(attribute)
It gives the no. of non-null values in the particular attribute
Count(*)
It gives the no. of tuples (including null )

3. 2) Select min(salary) from employee;
Aggregate function
Ex: 1) Select max(salary) from employee;
2) Select min(salary) from employee;
Output -1
TABLE - EMPLOYEE ID
NAME
SALARY
place 1
ARUN
6000
Dubai 2
VARUN
8000
Sharjah 3
ALI
9000
Ajman 4
GEORGE
12000 5
MOHD
dubai
max(salary)
12000
Output -2
min(salary)
6000

4. Select sum(salary) from employee; Select count (*) from employee;
Aggregate function
Ex: Select avg(salary) from employee;
Select sum(salary) from employee;
Select count (*) from employee;
TABLE - EMPLOYEE ID
NAME
SALARY
place 1
ARUN
6000
Dubai 2
VARUN
8000
Sharjah 3
ALI
9000
Ajman 4
GEORGE
12000 5
MOHD
dubai
Output -3
count(*) 5

5. Ex: Select max(salary) from employee where place = ‘Dubai’;
Aggregate function
Ex: Select max(salary) from employee where place = ‘Dubai’;
TABLE - EMPLOYEE ID
NAME
SALARY
place 1
ARUN
6000
Dubai 2
VARUN
8000
Sharjah 3
ALI
9000
Ajman 4
GEORGE
12000 5
MOHD
Output -1
max(salary)
8000

6. Ex: Select COUNT(*) from employee where place = ‘Dubai’;
Aggregate function
Ex: Select COUNT(*) from employee where place = ‘Dubai’;
TABLE - EMPLOYEE ID
NAME
SALARY
place 1
ARUN
6000
Dubai 2
VARUN
8000
Sharjah 3
ALI
9000
Ajman 4
GEORGE
12000 5
MOHD
Output -1
COUNT(*) 2

7. 2) Select COUNT(MARK) from employee;
Aggregate function
Ex:1) Select COUNT(*) from employee;
2) Select COUNT(MARK) from employee;
Output -1
TABLE - EMPLOYEE
COUNT(*) 5 ID
NAME
MARK 1
ARUN 50 2
VARUN 3
ALI 80 4
GEORGE 90 5
MOHD 78
Output -2
COUNT(mark) 4