add example of joining to labeled table
add example of joining to labeled table

wujuguang/sqlalchemy,epa/sqlalchemy,itkovian/sqlalchemy,alex/sqlalchemy,hsum/sqlalchemy,wfxiang08/sqlalchemy,bdupharm/sqlalchemy,graingert/sqlalchemy,davidfraser/sqlalchemy,hsum/sqlalchemy,276361270/sqlalchemy,Akrog/sqlalchemy,ThiefMaster/sqlalchemy,davidfraser/sqlalchemy,WinterNis/sqlalchemy,robin900/sqlalchemy,Cito/sqlalchemy,wfxiang08/sqlalchemy,pdufour/sqlalchemy,ThiefMaster/sqlalchemy,robin900/sqlalchemy,sandan/sqlalchemy,itkovian/sqlalchemy,alex/sqlalchemy,sqlalchemy/sqlalchemy,bootandy/sqlalchemy,Cito/sqlalchemy,brianv0/sqlalchemy,bdupharm/sqlalchemy,bootandy/sqlalchemy,graingert/sqlalchemy,epa/sqlalchemy,halfcrazy/sqlalchemy,276361270/sqlalchemy,monetate/sqlalchemy,Akrog/sqlalchemy,sandan/sqlalchemy,alex/sqlalchemy,Cito/sqlalchemy,olemis/sqlalchemy,inspirehep/sqlalchemy,monetate/sqlalchemy,davidjb/sqlalchemy,inspirehep/sqlalchemy,zzzeek/sqlalchemy,davidjb/sqlalchemy,WinterNis/sqlalchemy,elelianghh/sqlalchemy,brianv0/sqlalchemy,dstufft/sqlalchemy,olemis/sqlalchemy,wujuguang/sqlalchemy,dstufft/sqlalchemy,j5int/sqlalchemy,EvaSDK/sqlalchemy,pdufour/sqlalchemy,j5int/sqlalchemy,EvaSDK/sqlalchemy,elelianghh/sqlalchemy,halfcrazy/sqlalchemy