Sometimes, the data that a report requires originates in several data sources. For example, an application system generates monthly transaction data and the data for each month is saved in a separate CSV file, or a system saves data in different formats, such as XML and CSV.
Actuate BIRT Designer provides two options for combining data from multiple sources. You can create a union data set or a joined data set. The option you choose depends on the data structures and the results you want. Both options entail combining data sets, so before creating a union data set or a joined data set, you first create the individual data sets. For example, to combine data from an XML file with data from a CSV file, you must first create the XML data set and the flat file data set.
