Bug 207561 [Regression] Conversion errror when preview the attached report design
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/editors/SQLDataSetEditorPage.java
while ( it.hasNext( ) )
					schemaCombo.add( it.next( ).toString( ) );
			}
		}
		ArrayList schemaObjectList = new ArrayList( );
		if ( schemaList != null )
		{
			int numberOfSchema = 0;
			Preferences preferences = JdbcPlugin.getDefault( )
					.getPluginPreferences( );
			if ( preferences.contains( DateSetPreferencePage.USER_MAX_NUM_OF_SCHEMA ) )
			{
				numberOfSchema = preferences.getInt( DateSetPreferencePage.USER_MAX_NUM_OF_SCHEMA );
			}
			else
			{
				numberOfSchema = DateSetPreferencePage.DEFAULT_MAX_NUM_OF_SCHEMA;
				preferences.setValue( DateSetPreferencePage.USER_MAX_NUM_OF_SCHEMA,
						numberOfSchema );
			}
			
			cachedSchemaComboIndex = schemaCombo.getSelectionIndex( );
			if ( schemaCombo.getSelectionIndex( ) < 0 )
			{
				String schemaName = schemaCombo.getText( ).trim( );
				
				if(schemaName.length( )!=0)
				{
					DbObject schemaObj = new DbObject( schemaName,
							schemaName,