When aggregating measures in a fact table, which SQL clause is necessary to summarize results by attributes in a dimension table?

When aggregating measures in a fact table and wanting to summarize results based on attributes in a dimension table, the GROUP BY clause is essential. This clause allows you to group the data based on one or more columns, which are typically the attributes found in the dimension tables. By using GROUP BY, you can perform aggregate functions such as SUM, AVG, COUNT, etc., on the measures in the fact table while organizing the results according to the specified attributes in the dimension table.

For instance, if you wanted to calculate the total sales (a measure in the fact table) for each product category (an attribute in the dimension table), you would employ the GROUP BY clause to group the results by the product category. Each unique category would produce a separate row in the results, along with the aggregated total sales for that category.

In contrast, while the JOIN clause is utilized to combine rows from two or more tables based on a related column, it does not inherently perform aggregation. Similarly, the ORDER BY clause is designed to sort the result set but does not contribute to the task of summarizing data by attributes. Therefore, the use of GROUP BY is specifically required for aggregating measures based on attributes in a dimension table.