Bug 112287 It's better to transfer to "new data source" dialog when creating a new data set without existing data source.
Description: It's better to transfer to "new data source" dialog automatically when creating a new data set without existing data source. Steps to reproduce: 1. There is no existing data source. 2. Create a new data set. 3. It pops up hint message, saying that "there is no data source". Actual result: it's better to transfer to "new data source" dialog box now and help users create a new data source.
chart/org.eclipse.birt.chart.reportitem.ui/src/org/eclipse/birt/chart/reportitem/ui/ReportDataServiceProvider.java
* Generate computed columns for the given report item with the closest data
	 * set available.
	 * 
	 * @param handle
	 *            the handle of the report item. No aggregation created.
	 * 
	 * @return true if succeed,or fail if no column generated.
	 * @see DataUtil#generateComputedColumns(ReportItemHandle)
	 * 
	 */
	private List generateComputedColumns( ReportItemHandle handle )
			throws SemanticException
	{
		DataSetHandle dataSetHandle = handle.getDataSet( );
		if ( dataSetHandle == null )
		{
			dataSetHandle = DEUtil.getBindingHolder( handle ).getDataSet( );
		}
		if ( dataSetHandle != null )
		{
			List resultSetColumnList = DataUtil.getColumnList( dataSetHandle );
			ArrayList columnList = new ArrayList( );
			for ( Iterator iter = resultSetColumnList.iterator( ); iter.hasNext( ); )
			{
				ResultSetColumnHandle resultSetColumn = (ResultSetColumnHandle) iter.next( );
				ComputedColumn column = StructureFactory.newComputedColumn( handle,
						resultSetColumn.getColumnName( ) );
				column.setDataType( resultSetColumn.getDataType( ) );
				column.setExpression( DEUtil.getExpression( resultSetColumn ) );
				columnList.add( column );