All you say I understand this is just a quick reply I will go through the links A background in software is enough is a little patronising But I am not here to give you my CV just to help I worked for a company for about eight years doing object oriented databases not pretend ones flattening it to SQL or whatever so am well on the ins and outs of relational theory if you care for that kind of thing It sounds like a job for a reduced table set but I will check out what you are trying to achieve We won t just get it right we ll get it written I can t say too much about what I do professionally Best wishes S