GROUP BY In SQL Server

Introduction

In this article i will explain about what is Group By and how to use this in Sql Server.

What Is

Group By clause is used for grouping the records of the database table(s). This clause creates a single row for each group and this process is called aggregation. The GROUP BY statement is used in conjunction with the aggregate functions to group the result-set by one or more columns.To use group by clause we have to use at least one aggregate function in Select statement. We can use group by clause without where clause.

Practice

Here i am writing few sql queries  by using Group By clause. 

Synatax :

SELECT column_name, aggregate_function(column_name)
FROM table_name
WHERE column_name operator value
GROUP BY column_name;

Aggregate Function

This is an aggregate function such as the SUM, COUNT, MIN, MAX, or AVG functions.

using group By with Aggregate Functions :

Using SUM

 SELECT DepId, SUM(Salary) AS Total_Salaries
FROM Employees
GROUP BY DepId ;

Using COUNT

SELECT DepId, COUNT(*) AS TotalEmployees
FROM Employees
GROUP BY DepId ;

Using MAX

SELECT DepId, MAX(Salary) AS Max_Salaries
FROM Employees
GROUP BY DepId ;

Using MIN

SELECT DepId, MIN(Salary) AS Min_Salaries
FROM Employees
GROUP BY DepId ;