PostgreSQL Group Functions is a type of command which accepts ‘n’ number 0f values as input and return a single value.

PostgreSQL Group Functions can be of different types:

- sum()
- average()
- maximum()
- minimum()
- count()

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

Select Sum<column_name> from <table_name>;

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 sum function in the table.

SQLDB=# select * from employee22; emp_id | ename | sal | deptno ---------+-------+-------+-------- 1001 | mike | 14000 | 10 1002 | rambo | 25000 | 20 1003 | kate | 15500 | 10 1004 | jeo | 17000 | 20 1005 | finn | 27000 | 30 (5 rows) SQLDB=# select sum(sal) from employee22; sum(sal) ---------- 98500 (1 row)

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 in PostgreSQL Group Functions 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.

Select avg(column_name) from <table_name>;

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 average function in the table.

SQLDB=# select * from employee22; emp_id | ename | sal | deptno ---------+-------+-------+-------- 1001 | mike | 14000 | 10 1002 | rambo | 25000 | 20 1003 | kate | 15500 | 10 1004 | jeo | 17000 | 20 1005 | finn | 27000 | 30 (5 rows) SQLDB=# select avg(sal) from employee22; avg(sal) ------------ 27005 (1 row)

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.

Select maximum<column_name>from <table_name>;

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 maximum function in the table.

SQLDB=# select * from employee22; emp_id | ename | sal | deptno ----------+-------+-------+-------- 1001 | mike | 14000 | 10 1002 | rambo | 25000 | 20 1003 | kate | 15500 | 10 1004 | jeo | 17000 | 20 1005 | finn | 27500 | 30 (5 rows) SQLDB=# select max(sal) from employee22; max(sal) ---------- 27500 (1 row)

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.

Select minimum<column_name>from <table_name>;

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 minimum function in the table.

SQLDB=# select * from employee22; emp_id | ename | sal | deptno ---------+-------+-------+-------- 1001 | mike | 14000 | 10 1002 | rambo | 25000 | 20 1003 | kate | 15500 | 10 1004 | jeo | 17000 | 20 1005 | finn | 27000 | 30 (5 rows) SQLDB=# select min(sal) from employee22; min(sal) --------- 14000 (1 row)

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.

select count<column_name> from <table_name>;

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.

SQLDB=# select * from employee22; emp_id | ename | sal | deptno ---------+-------+-------+-------- 1001 | mike | 14000 | 10 1002 | rambo | 25000 | 20 1003 | kate | 15500 | 10 1004 | jeo | 17000 | 20 1005 | finn | 27000 | 30 (5 rows) SQLDB=# select count(emp_id) from employee22; count(emp_id) --------------- 5 --------------- (1 row)

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.

- PostgreSQL Group Functions – 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.