GROUP BY usage and examples

Overview

GROUP BY collects rows that share the same grouping keys, then applies aggregates such as SUM, COUNT, or AVG to each group. Regular selected columns should normally appear in GROUP BY. Use WHERE before grouping and HAVING to filter aggregate results afterward.

Basic syntax

SELECT department, SUM(amount) FROM orders GROUP BY department;

Examples

GROUP BY example

Group orders by department and sum amount so each department returns one aggregate row.

Sample table

Table：orders

orders
department	amount
Sales	1200
IT	900
Sales	1500
HR	700

Run result

result
department	SUM(amount)
HR	700
IT	900
Sales	2700

Common issues

Which columns should follow GROUP BY?

Use the columns you want to group by. Non-aggregate selected columns should usually appear in GROUP BY.

How is GROUP BY different from DISTINCT?

DISTINCT removes duplicates, while GROUP BY is mainly used with aggregates such as COUNT, SUM, and AVG.

Can GROUP BY use multiple columns?

Yes. For example, group by customer_id and status together.

Keep reading

COUNT SUM AVG HAVING GROUP_CONCAT MAX MIN COUNT DISTINCT

GROUP BY