Bug 199021 Error message pops up several times when click an invalid dataset
Description: There is a sqlserver datasource and dataset, remove the jtds driver to let the dataset invalid. Double click on the dataset, the error message will pop up serveral times. Build version:2.2.0.v20070807-0630 Steps to reproduce: 1. Create a sqlserver datasource and dataset. 2. Remove the jtds driver, and the dataset will be invalid. 3. Double click on the dataset. Expect result: Error message pops up once to indicate the problem. Actual result: Error message pops up serveral times.
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/editors/SQLDataSetEditorPage.java
return;
		}
		try
		{
			Image image = tableImage;
			if ( tablesRs != null )
			{
				int numberOfTable;
				Preferences preferences = JdbcPlugin.getDefault( )
						.getPluginPreferences( );
				if ( preferences.contains( DateSetPreferencePage.USER_MAX_NUM_OF_TABLE_EACH_SCHEMA ) )
				{
					numberOfTable = preferences.getInt( DateSetPreferencePage.USER_MAX_NUM_OF_TABLE_EACH_SCHEMA );
				}
				else
				{
					numberOfTable = DateSetPreferencePage.DEFAULT_MAX_NUM_OF_TABLE_EACH_SCHEMA;
					preferences.setValue( DateSetPreferencePage.USER_MAX_NUM_OF_TABLE_EACH_SCHEMA,
							numberOfTable );
				}
				int count = 0;
				while ( tablesRs.next( ) && count < numberOfTable )
				{
					String tableName = tablesRs.getString( "TABLE_NAME" );
					String type = tablesRs.getString( "TABLE_TYPE" );
					if ( type.equalsIgnoreCase( "SYSTEM TABLE" ) )
						continue;
					
					
					int dbType = DbObject.TABLE_TYPE;