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| Content Provider | ACM Digital Library |
|---|---|
| Author | Bradley, J. |
| Copyright Year | 1978 |
| Abstract | A data model is presented, based on the extension of the concept of a DBTG owner-coupled set to permit $\textit{static}$ and $\textit{dynamic}$ sets and a new kind of set referred to as a $\textit{virtual}$ set. The notion of connection fields is introduced, and it is shown how connection fields may be used to construct derived information bearing set names, and hence permit the specification of (dynamic) sets which are not predeclared in a schema. Virtual sets are shown to reflect the functional dependencies which can exist within a file. A technique which permits the data model to be fully described diagrammatically by extended Bachman diagrams is described. A predicate calculus for manipulation of this data model is presented. Expressions written in this calculus are compared with corresponding expressions in a relational predicate calculus, DSL ALPHA. An argument for the relational completeness of the language is given. |
| Starting Page | 385 |
| Ending Page | 416 |
| Page Count | 32 |
| File Format | |
| ISSN | 03625915 |
| e-ISSN | 15574644 |
| DOI | 10.1145/320289.320294 |
| Volume Number | 3 |
| Issue Number | 4 |
| Journal | ACM Transactions on Database Systems (TODS) |
| Language | English |
| Publisher | Association for Computing Machinery (ACM) |
| Publisher Date | 1978-12-01 |
| Publisher Place | New York |
| Access Restriction | One Nation One Subscription (ONOS) |
| Subject Keyword | Codasyl DBTG DSL AlPHA Connection field Dynamic set Extended Bachman diagram Extended owner-coupled set data model Extended owner-coupled set predicate calculus Functional dependency Information bearing set name Owner-coupled set Static set Virtual set |
| Content Type | Text |
| Resource Type | Article |
| Subject | Information Systems |
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