J. Paredaens, P. De Bra, M. Gyssens, D. Van Gucht, "The Structure of the Relational Data Model," Springer-Verlag, Berlin, 1989.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....In this paper we developed type systems and languages for databases with partial information. The next important step will be to accommodate traditional 31 database constraints into the model. Relatively little is known about constraints in relational databases with nulls (see [AM86, Gra91, PDGV89, Tha91, Tha89] and virtually nothing is known about constraints for other kinds of partial information. To the best of our knowledge, no work has been done on understanding how the ordering interacts with constraints. There are several possible approaches to the study of interaction of ....

J. Paredaens, P. De Bra, M. Gyssens and D. Van Gucht, "The Structure of the Relational Data Model", Springer, Berlin, 1989.

....continue to hold for bags and which do not. One of the claims of the paper is that considering bags instead of sets allows us to obtain a rational reconstruction of SQL. In some books, even a statement that SQL is equivalent to the relational algebra can be found. For example, Paredaens et al. [45] state that the tuple relational calculus and SQL have the same expressive power. While no one really knows what SQL is, since there are many different versions, it is widely accepted that any version of SQL has at least two features which are not present in the relational algebra: ffl SQL ....

J. Paredaens, P. De Bra, M. Gyssens, D. Van Gucht, "The Structure of the Relational Data Model," Springer-Verlag, Berlin, 1989.

....all others put together. Rejecting a nice idea of Peter Buneman to call it the kitchen sink powerdomain, I shall use the salad powerdomain instead. Let me first motivate the use of the edible powerdomains. Since late 70s, many researchers tried to understand partial information in databases; [1, 14, 9, 23, 6, 5, 17] name just a few of the many books and papers in this area. In [5, 6] Buneman and others proposed to recast the main principles of relational databases in domain theory. The ordering on objects was interpreted as partiality, i.e. x y means that x is more partial than y, or y is more informative ....

J. Paredaens et al., "The Structure of the Relational Data Model", Springer, Berlin, 1989.

....establish the connection between data models and types, i.e. to represent database objects (not necessarily relational databases) as typed objects in programming languages. There have been made a number of attempts to generalize relational databases giving up the firstnormal form assumption, see [1, 4, 6, 9, 10, 13, 16, 17, 18, 20]. They can be divided into two categories. The first one consists of models that do not contain sets. Usually it means that they admit null values and or record structures, the latter including also case, or discriminated union. In this case [5] provides us with the idea how to develop the ....

....discuss the concept of the complement of a scheme. This concept is necessary in order to introduce multivalued dependencies. Multivalued dependencies having been introduced, we may try to define join to generalize the result that establishes connection between joins and multivalued dependencies [24, 16]. The concept of join for the domain model was introduced in [5] as a supremum in the Smyth powerdomain ordering [22] We will show that in a certain type of domains multivalued dependencies are in one to one correspondence with the decompositions of relations. The model proposed in [5] does not ....

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J. Paredaens, P. De Bra, M. Gyssens, D. Van Gucht. The Structure of the Relational Datamodel. Springer-Verlag, Berlin, 1989.

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J. Paredaens, P. De Bra, M. Gyssens, D. Van Gucht, "The Structure of the Relational Data Model," Springer-Verlag, Berlin, 1989.

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