# SQL: Top Customers and Key Accounts with GROUP BY and HAVING

> A beginner SQL walkthrough in the free DB Fiddle: total revenue per customer with GROUP BY, sort the biggest to the top, keep the top three with LIMIT…

Source: https://learn.ynteractive.com/content/sql-top-customers · Updated 2026-10-24 · Free from Stepthrough (https://learn.ynteractive.com)

## Practice it step by step

[Start the free practice](https://learn.ynteractive.com/modules/sql-top-customers)

[Take the free module: why it matters, practice and a quick check →](https://learn.ynteractive.com/courses/sql-for-business-reports/2)

You do every step yourself in a practice copy of DB Fiddle. It checks your work as you go, and “Do it for me” finishes any step you get stuck on. Free, about 12 minutes, and nothing touches your real accounts. [Open full screen](https://learn.ynteractive.com/modules/sql-top-customers)

Free · Live now · [SQL](https://learn.ynteractive.com/content/course/sql) · [DB Fiddle](https://learn.ynteractive.com/content/tool/db-fiddle) · ~12 min · 14 steps · Beginner

Updated October 24, 2026. Built against the tool’s current screens and checked step by step. [How we check this lesson](https://learn.ynteractive.com/content/about#how-we-check)

A beginner [SQL](https://learn.ynteractive.com/content/glossary/sql) walkthrough in the free DB Fiddle: total revenue per customer with [GROUP BY](https://learn.ynteractive.com/content/glossary/group-by), sort the biggest to the top, keep the top three with LIMIT and list key accounts with HAVING.

## At a glance

| Question | Answer |
| --- | --- |
| What you build | A beginner SQL walkthrough in the free DB Fiddle: total revenue per customer with GROUP BY, sort the biggest to the top, keep the top three with LIMIT and list key accounts with HAVING. |
| Tools | DB Fiddle |
| Time | About 12 minutes, 14 steps in 3 parts |
| Level | Beginner, no coding needed |
| Cost | Free |
| Ways to learn it | [Practice it step by step](https://learn.ynteractive.com/modules/sql-top-customers) |

### The 3 parts, in short

1. Make the orders table: Click in Schema SQL, Create the orders table, Add the first two orders, Add three more orders, and 1 more step.
2. Total each customer: Total each customer, Run it, Biggest first, Run it, and 2 more steps.
3. Key accounts with HAVING: Count orders too, Keep accounts over $3,000, Run it.

**Start here first:** [SQL: Build a Monthly Revenue Report from an Orders Table](https://learn.ynteractive.com/content/sql-monthly-revenue-report) (module 1 of SQL)

## What you'll build

The owner of Lakeside Office Supply (made up) wants two lists before the [quarterly review](https://learn.ynteractive.com/content/glossary/quarterly-business-review): the top three customers, and every 'key account' worth $3,000 or more this quarter so each gets a thank-you call. Priya would normally sort a spreadsheet and add up each customer by hand. In this lesson you type the same orders table into [DB Fiddle](https://learn.ynteractive.com/content/tool/db-fiddle) and answer both questions with GROUP BY, ORDER BY, LIMIT and HAVING, typing every line yourself.

Cobalt Legal ($4,440 from 3 orders) and Northside Realty ($4,030 from 2) are the key accounts; Maple Dental ($2,230) completes the top three. Change 3000 in the HAVING line and the list updates for any threshold. Do it in DB Fiddle yourself: the lesson page has the checklist.

- Tools: DB Fiddle
- Time: about 12 minutes, 14 steps in 3 chapters
- Level: beginner, no coding needed
- Price: free

## Practice first, then build it for real

Practice copy built from real DB Fiddle screens (db-fiddle.com, MySQL v9, captured 24 October 2026). Every query in it was typed and run there. The shop, its customers and its orders are made up; the ad box on the left is blurred. To build it for real you need your own DB Fiddle account, and some services charge once you use them for real work, so check each tool's current pricing.

## Try it yourself, free

Reading the steps is a start. Doing them is how it sticks. The interactive module walks you through every click in a practice copy of DB Fiddle, checks each step, and never touches your real accounts.

[Start “SQL: Top Customers and Key Accounts with GROUP BY and HAVING”](https://learn.ynteractive.com/modules/sql-top-customers)

## Step by step: SQL: Top Customers and Key Accounts with GROUP BY and HAVING

All 14 steps of the interactive module, in order. In the module you watch each one, then do it yourself in a practice copy that checks your work.

### 1. Make the orders table

1. **Click in Schema SQL.** Open **db-fiddle.com** (no account needed). The left box, **Schema SQL**, is where the table goes. Click inside it.
   This is DB Fiddle, a free database in your browser.
2. **Create the orders table.** Type these three lines. They make an empty table with four columns: an id, the order date, the customer and the amount. In the practice you can type it on one line; in DB Fiddle press Enter between lines.
3. **Add the first two orders.** Leave a blank line, then type the INSERT line and the first two orders. Text goes in single quotes; numbers do not.
   Names in single quotes.
4. **Add three more orders.** Type the next three orders. Each row ends with a comma.
   Three more orders. Each row ends with a comma.
5. **Add the last three orders.** Type the last three. The very last row ends with a semicolon instead of a comma: that tells the database the statement is finished.
   The last three orders. The very last one ends with a semicolon, not a comma.

### 2. Total each customer

6. **Total each customer.** In **Query SQL**, type a query that adds up the amount for each customer. **GROUP BY customer** makes one row per customer.
   In the Query SQL box, type a query that adds up each customer, with GROUP BY customer.
7. **Run it.** Click **Run**.
8. **Biggest first.** One row per customer, in no useful order. Click at the end of the last line, delete the semicolon, press Enter and type the line shown below. **DESC** means descending: biggest first.
   Now sort it. Remove the semicolon and add ORDER BY revenue DESC, biggest first.
9. **Run it.** Click **Run**.
   Run it.
10. **Keep the top three.** Cobalt Legal is on top with $4,440. For a top-three list, remove the last semicolon again and add one line.
    Cobalt Legal is on top. Add LIMIT 3 to keep only the top three.
11. **Run it.** Click **Run**.
    Run it.

### 3. Key accounts with HAVING

12. **Count orders too.** Now the key accounts. Replace the query (Ctrl+A, then type) and start with three lines. COUNT(*) adds the number of orders next to the revenue.
    Now the key accounts. Replace the query, and count the orders as well as the revenue.
13. **Keep accounts over $3,000.** Add three lines. **HAVING** filters the totals after they are added up, so it can say "only customers whose total is at least 3000".
    Add GROUP BY customer, HAVING the total at least three thousand, and the sort.
14. **Run it.** Click **Run**.
    Run it.

## Screenshots

[Start this module free](https://learn.ynteractive.com/modules/sql-top-customers)

- Previous in SQL: [SQL: Build a Monthly Revenue Report from an Orders Table](https://learn.ynteractive.com/content/sql-monthly-revenue-report)
- Next in SQL: [SQL: Find Customers Who Have Gone Quiet with a LEFT JOIN](https://learn.ynteractive.com/content/sql-quiet-customers)

## Free cheat sheet

Print it or save the PDF: the key steps and checks from this lesson on one page, free.

- [SQL Business Reports Cheat Sheet](https://learn.ynteractive.com/content/cheat-sheets/sql-business-reports): A free one-page SQL cheat sheet: SELECT, WHERE, SUM, GROUP BY, HAVING, ORDER BY, LIMIT and LEFT JOIN, with the three report queries from the course.

[All free printable cheat sheets](https://learn.ynteractive.com/content/cheat-sheets)

## Terms in this lesson

Plain-English definitions, each with an example from a free lesson.

[GROUP BY (SQL)](https://learn.ynteractive.com/content/glossary/group-by) · [SQL](https://learn.ynteractive.com/content/glossary/sql)

[The full AI glossary](https://learn.ynteractive.com/content/glossary)

## Browse related tutorials

[SQL (3)](https://learn.ynteractive.com/content/course/sql) · [DB Fiddle tutorials (3)](https://learn.ynteractive.com/content/tool/db-fiddle)

Want AI working like this in your business? Robert Breen, the instructor behind this lesson, helps small and mid-sized teams put AI assistants, agents and automations to work. [See Ynteractive’s AI consulting](https://ynteractive.com/)