Aggregate Functions: SUM COUNT AVG MIN MAX

By Ravindra Bagale Last updated: 31 October 2026

Lessons in this chapter:

11.1 What an Aggregate Does (Many Rows → One Number)
11.2 SUM and AVG on Money Columns (₹ $ £ €)
11.3 COUNT(*) vs COUNT(DISTINCT column)
11.4 MIN and MAX for Dates and Amounts
11.5 Practice: City Totals on raja_coffee Orders

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Ravi Sir's Cards for this chapter

SUM, COUNT and AVG aggregates. Managers often want one number, like total sales, the number of orders or the average order value.

Revision card What is the difference between COUNT(*) and COUNT(column)? COUNT(*) counts every row. COUNT(column) counts only the rows where that column is not NULL.

What is the difference between COUNT(*) and COUNT(column)? COUNT(*) counts every row. COUNT(column) counts only the rows where that column is not NULL.

Interview card Aggregate without GROUP BY. When you use an aggregate like SUM without GROUP BY, SQL returns one row for all the rows you kept.

Comparison card

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