Cross-tab reports group data in two dimensions (down and across). They are useful for summarizing large amounts of data in a format that cross-references information.

To create cross-tab reports, you will typically start with a GROUP BY query to summarize the data into rows, and then use a transformation (pivot) service to create the grouped columns. The transformation service can be provided by the database server itself, it can be a custom program, or you can use C1Report's built-in domain aggregates.

In all cases, the most important element in the cross-tab report is the original summarized view of the data. For example, a typical summarized view would look like this:

This data would then be transformed by adding columns for each quarter and consolidating the values into the new columns:

You can do this using C1Report aggregate functions. The report would be grouped by year. The Detail section would be invisible, and the group header would contain the following aggregates:

The first aggregate would calculate the total amount sold in the current year. The quarter-specific aggregates specify a domain to restrict the aggregate to the specified quarter.

For the complete report, see report "20: Cross-tab Reports" in the CommonTasks.xml report definition file, which is available in the ComponentOne Samples folder.