Question

If both nonaggregated and aggregated columns are used in the SELECT clause, the GROUP BY clause must contain the nonaggregated columns?

Answer 1

When using both nonaggregated and aggregated columns in the SELECT clause, the GROUP BY clause should contain the nonaggregated columns.

Step-by-step explanation:

When using both nonaggregated and aggregated columns in the SELECT clause, the GROUP BY clause should contain the nonaggregated columns. This is because the GROUP BY clause is used to group the rows in the result set based on the values of the specified columns. When a column is included in the SELECT clause without any aggregate functions like SUM or COUNT, it is considered a nonaggregated column.

For example, suppose you have a table called 'Sales' with columns 'Product', 'Region', and 'SalesAmount'. If you want to calculate the total sales amount for each product category and region, you can use the following query:

SELECT Product, Region, SUM(SalesAmount) FROM Sales GROUP BY Product, Region;

In this query, the nonaggregated columns 'Product' and 'Region' are included in the GROUP BY clause as well.