Group By in SQL With Example [ COUNT, AVG, MAX, MIN ,SUM ] Video

Learning Group By in SQL is a little bit tricky for a newbie programmer. In today’s lesson, I will give in-depth discussion about Group By in SQL with Example using Aggregate functions.

Few Questions and Answers in learning SQL Group By Functions

Lesson Objectives

Here’s the main objectives after completing this lesson, you will be able to do the following:

• Identify the available Group Functions
• Describe the use of group functions
• Aggregate data using GROUP BY clause
• Include or Exclude grouped rows by using the HAVING clause

Types of group functions

The GROUP BY statement is often used with aggregate functions (AVG, COUNT, MAX, MIN, and SUM) to group the result-set by one or more columns.

Group Functions Syntax

SELECT (column,...), group_function(column)
FROM (table)
WHERE (condition)
[GROUP BY (column)]
[ORDER BY (column)]

Sample table used in this lesson

Watch the Video demonstration here:

Count with group by statement

The following SQL statement finds the number of Employee by Department:

SQL Group by Count Statement

SELECT DEPT_NAME, COUNT(EMP_ID) AS "No of Employee" FROM tblsampleemployee GROUP BY DEPT_NAME

Results of Count with group by Statement

SQL Group by using AVG

The following SQL statement finds the average SALARY of all Employee:

SQL statement using AVG

SELECT AVG(SALARY) AS "Average Salary" FROM tblsampleemployee

RESULT

AVG with Group By in SQL Example

The following SQL statement finds the average SALARY of all Employee by Department:

Another SQL statement using AVG

SELECT DEPT_NAME, AVG(SALARY) AS "Average Salary" 
FROM tblsampleemployee GROUP BY DEPT_NAME

SQL group by Example Results

Query using MAX AND MIN With group by statement

The following SQL statement finds the Maximum and Minimum Salary by Department:

Group by in SQL Statement

SELECT DEPT_NAME, MAX(SALARY) AS "Maximum Salary", MIN(SALARY) AS "Minimum Salary" FROM tblsampleemployee GROUP BY DEPT_NAME

Results of Using MAX and MIN

Query using SUM With Group by statement

The following SQL statement finds the Payroll by Department:

Group by statement using SUM

SELECT 
DEPT_NAME, sum(SALARY) AS "PAYROLL" 
FROM tblsampleemployee 
GROUP BY DEPT_NAME 
ORDER BY DEPT_NAME

Results

Excluding group results: The having clause

Use the HAVING clause to restrict groups:

1. Rows are grouped.
2. The group function is applied.
3. Groups matching the Having clause are displayed.

Syntax of Group by HAVING in SQL

SELECT (column,...), group_function(column)
FROM (table)
WHERE (condition)
[GROUP BY group_by_expression]
[HAVING group_condition]
[ORDER BY (column)]

Example: The following SQL statement finds the Total Payroll exceeding 80,000.00 by Department.

SQL Statement Using Having Clause

SELECT
DEPT_NAME, sum(SALARY) AS "PAYROLL"
FROM tblsampleemployee
GROUP BY DEPT_NAME
HAVING SUM(SALARY) > 80000
ORDER BY DEPT_NAME

Results of using Having Clause

Based on the example of using HAVING Clause, it displays the DEPT_NAME and PAYROLL that exceeds 80000. You will also notice that the EXECUTIVE department has been excluded and the list is sorted by Department Name.

NOTE: You can use the HAVING clause to specify which groups are to be displayed, and thus, you further restrict the groups on the basis of aggregate information.

Summary

In this lesson, you should have learned how to:

• Use the functions AVG, COUNT, MAX, MIN, SUM
• Write queries that use the Group By clause
• Write queries that use the Having Clause

Related Article

• Best JOINS In SQL With Examples 2020 | Video Tutorial
• Writing Basic SQL Select Statements With Actual Demonstration
• SQL SELECT Statement WHERE | Restricting and Sorting of Data
• Logical Operators In SQL [ AND, OR, NOT ]
• Best MySQL Tutorial For Beginners in 7 Days
• DBMS Mini Projects Topics for Students 2021

Inquiries

I hope that you have learned something new today. If you have any questions or suggestions about the Group by in SQL with examples, please feel free to leave a comment below.