Aggregations

Lesson in the Ruby on Rails Roadmap · Stage 7: Active Record

Last updated 14 September 2026

What is Aggregations?

Aggregations in Active Record allow you to derive summary information from your database records. This involves performing calculations like finding the average, minimum, maximum, or sum of values across a set of records, or counting the number of records that meet certain criteria. These calculations are typically performed directly within the database for efficiency and can be easily accessed through your Rails models.

Study this in the interactive course See the whole Ruby on Rails roadmap

Free resources to learn Aggregations

Official docsGrouping
Official docsCalculations
ArticleGrouping and Aggregating
VideoSQL Learning Path - Group By Statement

Aggregations: common questions

Can I learn Aggregations in Hindi?

This lesson is written in English. Once you sign in, open it in the interactive course and ask the AI tutor to explain Aggregations in Hindi or Hinglish. The tutor answers from this lesson’s own text, so it stays on the syllabus, and it runs on your own Google, OpenAI or Anthropic key.

Is this Aggregations tutorial for beginners?

It is lesson 40 of 98 in the free Ruby on Rails roadmap, in stage 7, Active Record. If you are new to Ruby on Rails, start from stage 1 and come back here in order; if you already know the earlier stages, this lesson stands on its own.