a technique for translating states between database schemata
Consider two database schemata modeling the same reality. Given a state of the first schema, we can ask what information it provides about the state of the second schema. It turns out that this information can be represented by a table similar to a tableau of Aho, Sagiv and Ullman. We show a simple method to construct this table, by using results developed for tables of this type in the context of representing incomplete information in relational databases. We also consider a closely related notion of equivalence of database schemata, briefly sketching a method to test two schemata for equivalence.
database schema model informal tables method context incomplete information relational database sketching test