When reshaping data with multiple monthly sales columns, what approach achieves the desired format of a single sales column?

The correct approach to achieve a single sales column from multiple monthly sales columns is unpivoting. Unpivoting transforms a dataset from a wide format, where you have separate columns for each month's sales, into a long format, where all sales figures are contained within a single column, and another column specifies the month associated with each sales figure.

This transformation is particularly useful for analysis and visualization, as many reporting tools, including Power BI, work more effectively with data in a long format. By unpivoting, you can more easily aggregate sales data over different dimensions or create more flexible visualizations that focus on trends over time.

In contrast, pivoting refers to the opposite process, where data is transformed from a long format into a wide format, creating new columns based on unique values in a specified field, which wouldn't be appropriate here. Appending involves stacking additional rows of data on top of existing rows, usually from similar datasets, while merging combines datasets based on a common key, typically used to bring in related or complementary data rather than to reshape existing column formats.