GROUPING SETS in SQL

GROUPING SETS in SQL is a powerful feature that allows you to create multiple groupings in a single query. It extends the capabilities of the GROUP BY clause by providing a way to generate multiple levels of aggregation in one statement, which can be particularly useful for reporting and data analysis.

Stax:

Explanation:

• column1, column2: Columns on which you want to perform grouping.
• aggregate_function(column3): An aggregate function like SUM(), COUNT(), AVG(), etc., applied to another column.
• GROUPING SETS: A clause that specifies multiple groupings.

And suppose the table contains the following data:

To generate multiple levels of aggregation, you can use GROUPING SETS as follows:

Output:

Explanation:

• (product_id): Aggregates sales by product_id.
• (region): Aggregates sales by region.
• (product_id, region): Aggregates sales by product_id and region.
• (): Calculates the grand total.

yntax:

Explanation:

• column1, column2: Columns on which you want to perform grouping.
• aggregate_function(column3): An aggregate function like SUM(), COUNT(), AVG(), etc., applied to another column.
• GROUPING SETS: A clause that specifies multiple groupings.

And suppose the table contains the following data:

To generate multiple levels of aggregation, you can use GROUPING SETS as follows:

Output:

Explanation:

• (product_id): Aggregates sales by product_id.
• (region): Aggregates sales by region.
• (product_id, region): Aggregates sales by product_id and region.
• (): Calculates the grand total.

Advantages of GROUPING SETS

1. Multiple Aggregations in One Query: You can calculate various aggregation levels with a single query, reducing the complexity and improving readability.
2. Efficiency: It is more efficient than writing multiple UNION queries for each grouping set.
3. Flexibility: Provides a flexible way to generate complex reports with different levels of aggregation.