Sql Aggregates — Free Sql Tutorial

TL;DR: Learn Sql Aggregates in Sql with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.

Sql Aggregates in Sql

Aggregate functions perform calculations on a set of rows and return a single value. Key functions: COUNT() (count rows), SUM() (total), AVG() (average), MAX() (highest), MIN() (lowest).

GROUP BY divides rows into groups based on column values, then applies the aggregate function to each group. For example: average marks per class, count of students per city.

HAVING filters groups (like WHERE filters rows). Use HAVING to filter on aggregate results: HAVING AVG(marks) > 85.

SELECT COUNT(*) FROM students;
SELECT AVG(marks) FROM students;
SELECT MAX(marks), MIN(marks) FROM students;

SELECT class, AVG(marks)
FROM students
GROUP BY class
HAVING AVG(marks) > 80;

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