Inner Joins Versus Outer Joins

In short, an inner join includes only data that is common to all components of the join. An outer join includes data that applies to all components. The following descriptions use an example of a report containing the Region attribute, the Sales metric, and the Budget metric:

• By default, inner joins are generated for all metrics in a report. The resulting report contains only those rows that have data returned for all the metrics. If a particular region does not have both sales and budget data, the region is not included on the report.
• If you switch to outer joins for all the metrics on the report, all rows with data for any of the metrics are displayed. All regions are included in the report, even if they have no data for one of the metrics.

You can specify different joins for each of the metrics on a report. For example, use an outer join for the Sales metric and an inner join for the Budget metric. The resulting report displays all regions with sales data. If a particular region has budget data but not sales data, the region is not included in the report.

For a more detailed explanation of this example, with report samples, see the Analyzing Data chapter of the Basic Reporting Help.