Functions Function is a type of command which accepts 'n' number of values as input and return a single value. MySQL Functions can be of different types:

Sum() - Calculate the set of values of an expression Avg() - Perform the average of an expression Maximum() - Perform the maximum value of an expression Minimum() - Perform the minimum value of an expression Count() - Perform count of an expression

The function sum() is used to calculate the set of values or an expression. For example, the sum function is used to add all the column details like salaries of employees.

table_name => Any accurate table. column_name => The operation that one can perform on a column in the table.

Below is an example to understand the concept of sum function in the table. [sql]mysql>select * from employee; +--------+-------+-------+--------+ | emp_id | ename | salary| deptno | +--------+-------+-------+--------+ | 1001 | mike | 12000 | 10 | | 1002 | rambo | 13000 | 20 | | 1003 | kate | 14000 | 10 | | 1004 | jeo | 14000 | 20 | | 1005 | finn | 14000 | 30 | +--------+-------+-------+--------+ 5 rows in set (0.00 sec) mysql> select sum(salary) from employee; +-----------+ |sum(salary)| +-----------+ | 67000 | +-----------+ 1 row in set (0.00 sec) mysql> select sum(salary)as total salary from employee; +--------------+ | Total salary | +--------------+ | 67000 | +--------------+ 1 row in set (0.00 sec)[/sql] The above example tells that, when sum() functional operation is performed on a column name like salary, then it will add all the employee salaries and gives the output.

Average function is used to calculate the average of a given arrangement of values or an expression. For example the average function is utilized to compute the average of a column name salary in the table.

table_name => Any accurate table. column_name => The operation that one can perform on a column in the table. 

Below is an example to understand the concept of average function in the table. [sql]mysql> select * from employee; +--------+-------+-------+--------+ | emp_id | ename | salary| deptno | +--------+-------+-------+--------+ | 1001 | mike | 12000 | 10 | | 1002 | rambo | 13000 | 20 | | 1003 | kate | 14000 | 10 | | 1004 | jeo | 14000 | 20 | | 1005 | finn | 14000 | 30 | +--------+-------+-------+--------+ 5 rows in set (0.00 sec) mysql>select avg(salary) from employee; +------------+ | avg(salary)| +------------+ | 13400.0000 | +------------+ 1 row in set (0.00 sec)[/sql] The above example tells that, when avg() functional operation is performed on a column name like salary, then it will average all the employee salaries and gives the output.

Maximum function is utilized to ascertain the most extreme value of a given arrangement of values or an expression. For illustration the maximum function is utilized to locate the maximum of a column name salary in the table.

table_name => Any accurate table. column_name => The operation that one can perform on a column in the table.

Below is an example to understand the concept of maximum function in the table. [sql]mysql> select * from employee; +--------+-------+-------+--------+ | emp_id | ename | salary| deptno | +--------+-------+-------+--------+ | 1001 | mike | 12000 | 10 | | 1002 | rambo | 13000 | 20 | | 1003 | kate | 13500 | 10 | | 1004 | jeo | 14000 | 20 | | 1005 | finn | 14500 | 30 | +--------+-------+-------+--------+ 5 rows in set (0.00 sec) mysql> select max(salary) from employee; +-----------+ |max(salary)| +-----------+ | 14500 | +-----------+ 1 row in set (0.00 sec)[/sql] The above example tells that, when max() functional operation is performed on a column name like salary, then it will display the highest salary of employee.

Minimum function is utilized to compute the base estimation of a given arrangement of values or an expression. For illustration the minimum function is utilized to locate the minimum of a column name salary in the table.

table_name => Any accurate table. column_name => The operation that one can perform on a column in the table.

Below is an example to understand the concept of minimum function in the table. [sql]mysql> select * from employee; +--------+-------+-------+--------+ | emp_id | ename | salary| deptno | +--------+-------+-------+--------+ | 1001 | mike | 12000 | 10 | | 1002 | rambo | 13000 | 20 | | 1003 | kate | 14000 | 10 | | 1004 | jeo | 14500 | 20 | | 1005 | finn | 14300 | 30 | +--------+-------+-------+--------+ 5 rows in set (0.00 sec) mysql> select min(salary) from employee; +------------+ | min(salary)| +------------+ | 12000 | +------------+ 1 row in set (0.00 sec)[/sql] The above example tells that, when min() functional operation is performed on a column name like salary, then it will display the lowest salary of employee.

Count function is utilized to compute the aggregate estimation of a given set of values or an expression. For illustration the count function is utilized to locate the aggregate number of employees in the table.

table_name => Any accurate table. column_name => The operation that one can perform on a column in the table.

Below is the example to understand the concept of count function in the table. [sql]mysql> select * from employee; +--------+-------+-------+--------+ | emp_id | ename | salary| deptno | +--------+-------+-------+--------+ | 1001 | mike | 12000 | 10 | | 1002 | rambo | 13000 | 20 | | 1003 | kate | 14000 | 10 | | 1004 | jeo | 14000 | 20 | | 1005 | finn | 14000 | 30 | +--------+-------+-------+--------+ 5 rows in set (0.00 sec) mysql> select count(emp_id) from employee; +---------------+ | count(emp_id) | +---------------+ | 5 | +---------------+ 1 row in set (0.00 sec)[/sql] The above example tells that, when count() functional operation is performed on a column name like emp_id, then it will count all the employees in the table and display the output as 5.

• Group function is used to accept 'n' number of values and return a single value.
• Sum functions adds, average calculates the average of set of values.
• Maximum and minimum functions calculates the maximum and minimum values in given set of values.
• Count gives total values.