Move MS SQL Express 2008 R2 to SQL Express 2012 for Team Foundation server 2012 to 2013 upgrade

It took me almost a day to try apply SQL 2008 R2 SP1, SP2 and SP3, still could not make the upgrade from TSF 2012 to 2013 successful. Eventually, I have to detach all SQL database first, then uninstall SQL 2008 R2 Express. Then install SQL 2012 Express, then attach database back. Then configure TFS to make the upgrade from TSF 2012 to TSF 2013 work.