Can I use multiple columns in GROUP BY?

Yes, you can group by multiple columns to create more specific groups.

Is HAVING mandatory when using GROUP BY?

No, HAVING is optional and used only when you want to filter groups based on aggregates.

What happens if I use WHERE with aggregate functions?

WHERE cannot filter on aggregate functions; you must use HAVING for that purpose.

Topic 9918 min readStructured Tutorial

SQL GROUP BY and HAVING - Real Examples Tutorial

Quick Answer

The SQL GROUP BY clause groups rows sharing a property so aggregate functions can be applied. HAVING filters these grouped results based on aggregate conditions. Together, they enable powerful data summarization and filtering in SQL queries.

Learning Objectives

Understand the purpose and syntax of the GROUP BY clause in SQL.
Learn how to use HAVING to filter grouped data based on aggregate conditions.
Apply GROUP BY and HAVING clauses in practical SQL queries with real examples.

Introduction

SQL GROUP BY and HAVING clauses are essential for summarizing and filtering grouped data.

GROUP BY organizes rows sharing common values, enabling aggregate functions like COUNT, SUM, AVG, MAX, and MIN.

HAVING filters these grouped results based on aggregate conditions, which WHERE cannot do.

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Author

RPATechnology Team

Last Updated

June 2026

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Introduction

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Introduction to Joins

INNER JOIN

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Understanding GROUP BY

Example: Counting Orders per Customer

Using HAVING to Filter Groups

Example: Customers with More Than 5 Orders

Real-World Examples

Example 1: Total Sales per Product

Example 2: Products with Sales Over $10,000

Example 3: Average Employee Salary by Department

Practical Example

Examples

Best Practices

Common Mistakes

Hands-on Exercise

Count Orders per Product

Filter Departments by Average Salary

Identify High-Selling Customers

Interview Questions

What is the difference between WHERE and HAVING in SQL?

Can you use HAVING without GROUP BY?

Why must all non-aggregated columns in SELECT appear in GROUP BY?

MCQ Quiz

1. What is the primary purpose of the SQL GROUP BY clause?

2. Which clause should you use to filter groups based on aggregate conditions after grouping?

3. Given a sales table, which query correctly finds products with total sales exceeding $10,000?

4. Why can't the WHERE clause be used to filter groups based on aggregate functions?

5. In the context of SQL GROUP BY and HAVING, what does the following query do? SELECT department_id, AVG(salary) AS avg_salary FROM employees GROUP BY department_id HAVING AVG(salary) > 70000;

Key Takeaways

Frequently Asked Questions

Can I use multiple columns in GROUP BY?

Is HAVING mandatory when using GROUP BY?

What happens if I use WHERE with aggregate functions?

Summary

FULL OUTER JOIN

SELF JOIN

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