Bug 153387 Database item can't be dragged and dropped onto editor field
Steps to reproduce: 1.Start up BIRT in Mac OS X; 2.File->New->Project; 3.File->New->Report Design; 4.In Data Explorer, create a New Data Source, and choose "Classic Models Inc. Sample DataBase", press "Next" and then press "finish"; 5.In Data Explorer, create a New Data Set, press "Next"; 6.In the popup window, expand the "CLASSICMODELS", select and drag a item onto the editor field at right side.
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/editors/SQLDataSetEditorPage.java
*/
	protected void createMetaDataProvider( )
	{
		if ( metaDataProvider == null )
		{
			metaDataProvider = new JdbcMetaDataProvider(null);		
		}
	}
	
	/**
	 *  Initializes the Jdbc related information , used  by this page
	 * ( such as the Jdbc Connection , Catalog Name etc )
	 * @param curDataSourceHandle
	 *
	 */
	protected void resetJdbcInfo(DataSourceDesign curDataSourceDesign)
	{
		if( metaDataProvider != null )
		{
			metaDataProvider.closeConnection( );
			metaDataProvider = null;
			createMetaDataProvider( );
			jdbcConnection = connectMetadataProvider( metaDataProvider, curDataSourceDesign);
			
			
			tableList = null;
			schemaList = null;
			schemaCombo.removeAll();
		}