A FlexReport definition can include several data sources, which are accessible through C1FlexReport.DataSources collection. The data sources in this collection are identified by unique names. These data sources can be used as:

• Main data source: It is the main data source for a report. The main data source is specified by using C1FlexReport.DataSourceName property on the report. If the main data source is not specified (DataSourceName is empty or contains a name not found in the DataSources collection), C1FlexReport is rendered in unbound mode, containing a single instance of the Detail section.
  
• Data source for Parameters: It is the source of valid values for the report parameters (elements in the C1FlexReport.Parameters collection). The data source for parameters is specified using ReportParameter.AllowedValuesDefinition.Binding.DataSourceName property.
  
• Data source for Charts: It is the data source for the Chart field. The data source for charts is specified using ChartField.DataSource property.

The list of supported data source types in FlexReport are as follows:

• OLE DB
• ODBC
• XML
• Object in external assembly
• Microsoft SQL Server Compact Data Provider version 3.5 and 4.0

For backwards compatibility with C1Report, C1FlexReport has a DataSource property which points to DataSources [DataSourceName]. When a new C1FlexReport is created, a single element with the name 'Main' is added to its C1FlexReport.DataSources collection, and 'Main' is assigned to the C1FlexReport.DataSourceName property.

Note that in C1Report, Main data source is the only data source for the report. 

Binding Data to Parameters in Multiple Data Source Report

Binding data to parameters defines the valid values for the report parameters (elements in the C1FlexReport.Parameters collection). The ReportParameter.AllowedValuesDefinition.Binding.DataSourceName property indicates the data source which is used to build the list of possible values in the parameters. The following code illustrates how to bind data to the parameters in a report with multiple data sources.

' add datasource and parameter using this datasource
Dim mds As DataSource = rep.DataSource
Dim ds As New DataSource()
ds.Name = "CategoriesDS"
ds.ConnectionString = mds.ConnectionString
ds.RecordSource = "select * from categories"
ds.DataProvider = DataProvider.OLEDB
rep.DataSources.Add(ds)
mds.RecordSource = "select * from products where categoryid = [CategoryParam]"
Dim rp As New ReportParameter()
rp.DataType = Doc.ParameterType.[Integer]
rp.Prompt = "Category"
rp.Name = "CategoryParam"
rp.AllowedValuesDefinition.Binding.DataSourceName = "CategoriesDS"
rp.AllowedValuesDefinition.Binding.ValueExpression = "CategoryID"
rp.AllowedValuesDefinition.Binding.LabelExpression = "CategoryName"
rep.Parameters.Add(rp)

// add datasource and parameter using this datasource
DataSource mds = rep.DataSource;
DataSource ds = new DataSource();
ds.Name = "CategoriesDS";
ds.ConnectionString = mds.ConnectionString;
ds.RecordSource = "select * from categories";
ds.DataProvider = DataProvider.OLEDB;
rep.DataSources.Add(ds);
mds.RecordSource = "select * from products where categoryid = [CategoryParam]";
ReportParameter rp = new ReportParameter();
rp.DataType = Doc.ParameterType.Integer;
rp.Prompt = "Category";
rp.Name = "CategoryParam";
rp.AllowedValuesDefinition.Binding.DataSourceName = "CategoriesDS";
rp.AllowedValuesDefinition.Binding.ValueExpression = "CategoryID";
rp.AllowedValuesDefinition.Binding.LabelExpression = "CategoryName";
rep.Parameters.Add(rp);