Bug 141959 Changing data set didn't clean old column bindings
Steps to reproduce: 1.Add two data sets, "ds1" and "ds2" 2.Add a table, binding with "ds1". All "ds1" column bindings generate automatically, that's good 3.Change "ds1" to None Expected result: All "ds1" column bindings should be cleaned Actual result: All "ds1" column bindings are still there. If changing to "ds2", "ds2" column bindings will be added after them.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ColumnBindingDialog.java
}
	private String getDataSetName( )
	{
		if ( inputElement.getDataSet( ) == null )
		{
			return NONE;
		}
		String dataSetName = inputElement.getDataSet( ).getQualifiedName( );
		if ( StringUtil.isBlank( dataSetName ) )
		{
			dataSetName = NONE;
		}
		return dataSetName;
	}
	private void startTrans( String name )
	{
		if ( isEnableAutoCommit( ) )
		{
			getActionStack( ).startTrans( name );
		}
	}
	private void commit( )
	{
		if ( isEnableAutoCommit( ) )
		{
			getActionStack( ).commit( );
		}
	}
	private void rollback( )
	{