#### How to join data sets

1. In Data Explorer, right-click Data Sets, and choose New Joint Data Set.
2. On the left of New Data Set, click the arrow button, and from the drop-down list, choose the first data set for the joint data set. The columns of the first data set appear.
3. On the right of New Data Set, choose the second data set for the joint data set. The columns of the second data set appear.
4. Select the columns to join. Select one column from the first data set, and one column from the second data set. Typically, you select the columns that are common to both data sets. BIRT Report Designer does not prevent you from selecting two unrelated columns as long as both columns have the same data type. Doing so, however, typically does not provide the results you want. Figure 3-11 shows an example of a joint data set definition.

Figure 3-11 Joint data set definition
5. Select a join type, then choose Finish.
6. On Edit Data Set, choose Preview Results to see the rows returned by the joint data set.