Ways to share data
As you have learned, a data set can provide data for multiple report elements of different types, and a cube can provide data for cross tabs and charts. This section reviews these two ways of sharing data, describes a third way for report elements to share data, and provides guidelines for using the different data-sharing methods.
Sharing a data set
Report elements can use the same data set if the data set returns the right amount and type of data for each element. For example, two tables can use the same data set if one table displays detailed data, and the other table displays the summary version of the same data. In the second report shown in Figure 25‑1, the two summary tables and the sales detail table use data from the same data set. Each report element that uses data from a single data set can sort, group, filter, or aggregate its data differently. For example, one table can sort sales data by country, and another table can sort the same data by sales total.
Sharing a cube
A cross tab must use data from a cube. A chart can use data from a data set or from a cube. If you create a cube for a cross tab and you want to display the same data in a chart, set up the chart to use the cube. Cube data is appropriate for a chart because a cube organizes data into dimensions (groups) and measures (aggregate data), which map well to a chart’s category series and value series. A cross tab and a chart that use data from the same cube can sort and filter their data differently.
Sharing data defined in another report element
This method is ideal for displaying the same data in multiple report elements, and for using the same sorting, groups, filters, and aggregations in every element. One report element is the primary element that determines how data is processed, and other elements use the data in the primary element. Typically, the primary element is a table or a cross tab, and charts use the data in those elements.
Another common example is a series of charts showing the same data. For example, to display identical data in a bar chart, a pie chart, and a line chart, one chart can be the primary element, and the other charts share the primary chart’s data. Data sharing among report elements is useful for building dashboard reports, described later.