How are aggregate functions related to GROUP BY?

SQLJunior~1 min read

Aggregate functions and GROUP BY work as a pair.

Aggregate functions (COUNT, SUM, AVG, MIN, MAX) process several rows and produce one value.
GROUP BY splits the table into groups of rows that share the same values in the chosen columns.

When used together: GROUP BY forms the groups -> aggregate functions compute a result for each group.

sql

SELECT department, SUM(salary)
FROM employees
GROUP BY department;

GROUP BY forms groups by department, and SUM() computes the salary total in each department separately.

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