What is the purpose of the GROUP BY clause in SQL?

The GROUP BY clause in SQL is specifically designed to aggregate data by grouping together rows that have the same values in specified columns. This means that when you use GROUP BY, you organize your result set into subsets that share common properties or values. For instance, if you have a sales table and you want to find the total sales per product, you would group the results by the product identifier. This allows you to perform aggregate functions, such as COUNT, SUM, AVG, etc., on these grouped subsets, providing meaningful summaries of your data.

The other options reflect different functionalities of SQL:

• Specifying the order of results returned relates to the ORDER BY clause, which organizes rows in a specific sequence based on one or more columns.

• Filtering results based on conditions pertains to the WHERE clause, which eliminates data that does not meet specific criteria before any grouping occurs.

• Combining records from multiple tables is typically accomplished using JOIN operations, which allow for the integration of data from two or more tables based on related columns.

Consequently, the purpose of the GROUP BY clause is best captured by the notion of grouping data by repeating values, thus enabling effective aggregation and analysis.