Bug 161191 Null is inserted when drag columns to query text with ctrl key pressed
Description: Null is inserted when drag columns to query text with ctrl key pressed Steps to reproduce: 1. New a data source. 2. New a dataset. 3. Press and hold ctrl key, select OFFICECODE and CITY columns, drag to query text. Expected result: "CLASSICMODELS.OFFICES.OFFICECODE,CLASSICMODELS.OFFICES.CITY" is inserted in query text. Actual result: "null,CLASSICMODELS.OFFICES.OFFICECODE,CLASSICMODELS.OFFICES.CITY" is inserted
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/editors/SQLDataSetEditorPage.java
}
		
		try
		{
			if ( jdbcConnection != null)
			{
				isSchemaSupported = metaDataProvider.isSchemaSupported();
			}
		}
		catch ( Exception e )
		{
			ExceptionHandler.showException( this.getShell( ),
					JdbcPlugin.getResourceString( "exceptionHandler.title.error" ),
					e.getLocalizedMessage( ),
					e );
		}
	}
		
	/**
	 * Called to indicate that the process of getting the available Db objects
	 * is in progress
	 * 
	 */
	private void setRefreshInfo( )
	{
		if ( rootNode == null )
		{
			return;
		}
		TreeItem item = new TreeItem( rootNode, 0 );