Some context would help but some (possibly relevant) possibilities: 1: If you have relation with 5 attributes you can generate tuples with all 5 attributes OR you can generate tuples with a subset of those attributes. Seems obvious but often these kinds of definitions are. 2: When looking at a relation you want to consider whether any subset of the attributes are dependent upon another attribute that is not a key for the relation. If so then that subset can likely be broken out into its own relation with the attribute that the subset relates to acting as a foreign key on the original relation. Without further context as to where and why the definition is being given further conclusions are tough to draw. My first point is simply an obvious property of how relations and attributes and the second relates to normalization of a relation schema. My $0.03 (inflation ya know) David J From: pgsql-general-owner@xxxxxxxxxxxxxx [mailto:pgsql-general-owner@xxxxxxxxxxxxxx] On Behalf Of Alpha Beta Hi, |
