>Thanks,Arnon. > >Just for my clarity, say we have > > Customer table -- Custcode is actual ( intended ) Candidate key > Invoice table -- Invoice No is original candidate key.I_custcode >was field used to relate to customer. > >Now we propose to relate with field I_custsurrogate . well you don't have to do that, it is usually better practice though (g) IAC once you add a surrogatekey you can turn the index of CustCode to regular >Should I_custcode field be dropped from Invoice table ?? Or would u suggest >to carry that field also ? no need to have the old forign key >Also , i recall having read somewhere about complications with Relations/RI >during data maintenance -- > 1) deleting index file and recreating indexes > 2) Zapping table and re-appending data >Can u please advise ? this is not related to the surrogate key issue this is related to the way the DBC handles the deletion of indexes etc. the problem is that if all the TAGs are deleted all the extended information stored in the DBC is being deleted as well you can solve this by yourself (given some work) but you may want to check out Stonfied Database Toolkit which will do this (and more) for you Arnon