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
tableType );
				tableList = new ArrayList( );
				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 )
						{