Introducing a cross tab
A cross tab is ideal for summarizing data in a compact and concise format. The aggregate values in a cross tab are arranged in dimensions and measures, and each cross tab can display multiple dimensions and multiple measures. The data for a cross tab is derived from a cube, which also arranges data in dimensions and measures. Dimensions are categories, such as products, customers, or sales periods, by which measures are aggregated. Measures represent values that are counted or aggregated, such as costs or units of products.
A cross tab has the following characteristics:
It requires at least three fields. In the example cross tab shown in
Figure 9‑1, the three fields are year, product line, and revenue.
One field populates the column headings in the cross tab. There is one column for each unique value in the field.
One field populates the row headings in the cross tab. There is one row for each unique value in the field.
One field’s values are aggregated, and these values populate the cells of the cross tab. In the example, each cell displays a sales total by product line, for each month and quarter, in the year 2004. The sales total is calculated by applying the SUM aggregate function across the values in the extended price field.