SQL -Structured Query Language - Sql Clause - Group By Clause Tutorial

THE ' GROUP BY ' clause is used to group records having similar values. It is used with aggregate functions like count, sum, avg, min, max.

Some of the examples are-

1. Calculate the number of employees in each department. (here we will use count()).
2. Find the maximum salary of the employee in each department. (here we will use max()).
3. Find the minimum salary of the employee in each department. (here we will use min()).
4. Calculate the average salary of the employee in each department. (here we will use avg()).
5. Calculate the sum of the salary of the employee in each department. (here we will use sum()).

Syntax-

The basic syntax of the GROUP BY statement with aggregate functions like count, sum, avg, min, max.

SELECT function_name(column_name),..,column_name_group 
FROM 
table_name 
GROUP BY 
column_name_group;

Here function_name can be count, sum, avg, min, max, and column_name_group is the name of the column to be group by.

For example –

SELECT COUNT(employee_id) 
FROM 
employees 
GROUP BY 
department_id;

In this statement, it will Calculate the number of employees in each department. (here we will use count())( Department wise - Group By Department ) 

SELECT MAX(salary) 
FROM 
employees 
GROUP BY 
department_id;

In this statement, it will find the maximum salary of the employee in each department. (here we will use max()).( Department wise - Group By Department ) 

SELECT MIN(salary) 
FROM 
employees 
GROUP BY 
department_id;

In this statement, it will find the minimum salary of the employee in each department. (here we will use min()). ( Department wise - Group By Department ) 

SELECT AVG(salary) 
FROM 
employees 
GROUP BY 
department_id;

In this statement, it will Calculate the average salary of the employee in each department. (here we will use avg()).( Department wise - Group By Department ) 

SELECT SUM(salary) 
FROM 
employees 
GROUP BY 
department_id;

In this statement, it will Calculate the sum of the salary of the employee in each department. (here we will use sum()).( Department wise - Group By Department )

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