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/provider/JdbcMetaDataProvider.java
metaData = null;
			}
			
		}
		if(jdbcConnection == null)
		{
			try
			{
				jdbcConnection = DriverLoader.getConnection( driverClass,
						url,
						userName,
						password );
				if ( jdbcConnection == null )
				{
					MessageDialog.openError( PlatformUI.getWorkbench( )
							.getDisplay( )
							.getActiveShell( ),
							JdbcPlugin.getResourceString("connection.test"),
							JdbcPlugin.getResourceString("connection.failed"));
				}
				else
				{
				    this.driverClass = driverClass;
				    this.url = url;
				    this.userName = userName;
				    this.pass = password;
				}
			}
			catch ( SQLException e )
			{