Incomplete Information in Relational Databases
Journal of the ACM (JACM)
An introduction to database systems: vol. I (4th ed.)
An introduction to database systems: vol. I (4th ed.)
Language features for flexible handling of exceptions in information systems
ACM Transactions on Database Systems (TODS)
A sound and sometimes complete query evaluation algorithm for relational databases with null values
Journal of the ACM (JACM)
Dynamic functional dependencies and database aging
Journal of the ACM (JACM)
A new normal form for nested relations
ACM Transactions on Database Systems (TODS)
A statistical approach to incomplete information in database systems
ACM Transactions on Database Systems (TODS)
A foundation of CODD's relational maybe-operations
ACM Transactions on Database Systems (TODS)
Limitations of record-based information models
ACM Transactions on Database Systems (TODS)
On semantic issues connected with incomplete information databases
ACM Transactions on Database Systems (TODS)
Extending the database relational model to capture more meaning
ACM Transactions on Database Systems (TODS)
System R: relational approach to database management
ACM Transactions on Database Systems (TODS)
The design and implementation of INGRES
ACM Transactions on Database Systems (TODS)
On Databases with Incomplete Information
Journal of the ACM (JACM)
Relational database: a practical foundation for productivity
Communications of the ACM
A relational model of data for large shared data banks
Communications of the ACM
Switching and Finite Automata Theory: Computer Science Series
Switching and Finite Automata Theory: Computer Science Series
Null values in data base management a denotational semantics approach
SIGMOD '79 Proceedings of the 1979 ACM SIGMOD international conference on Management of data
Embedding expert knowledge and hypothetical data bases into a data base system
SIGMOD '80 Proceedings of the 1980 ACM SIGMOD international conference on Management of data
Remarks on the algebra of non first normal form relations
PODS '82 Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems
Imprecise database: representation of imprecise and exceptional conditions via embedded relations
Imprecise database: representation of imprecise and exceptional conditions via embedded relations
Flexible Relations - Operational Support of Variant Relational Structures
VLDB '95 Proceedings of the 21th International Conference on Very Large Data Bases
Hi-index | 0.00 |
Exceptional conditions are anomalous data which meet the intent of a schema but not the schema definition, represent a small proportion of the database extension, and may become known only after the schema is in use. Admission of exceptional conditions is argued to suggest a representation that locally stretches the schema definition by use of relations with embedded subrelations. Attempted normalization of these relations to 1NF does not yield the static schema typically associated with such transformations. A class of relations, termed Exceptional Condition Nested Form (ECNF), is defined which allows the necessary representation of exceptional conditions while containing sufficient restrictions to prevent arbitrary and chaotic inclusion of embedded subrelations. Queries on a subset of exceptional conditions, the exceptional constraints, are provided an interpretation via an algorithm that transforms ECNF relations into 1NF relations containing two types of null values. Extensions of relational algebraic operators, suitable for interactive query navigation, are defined for use with ECNF relations containing all forms of exceptional conditions.