>A question came up in the exam chat today about which tier referential integrity should belong in.
>
>Reasons for it being in the data tier:
>- it has nothing to do with the business rules since it has nothing to do with the domain your are trying to model.
>- it only is factor with relational data
>
>Reasons for it being in the biz tier:
>- domain expert may make "relation integrity" statements like "if a sales person is fired, move all of their customers to his boss". Clearly this is a business rule.
>
>Comments and thoughts about this appreciated.

It definately belongs in the data tier. There may be biz rules that need to be enforced, but the implementation belongs in the data tier.