On the Use of Marked Nulls for the Evaluation of Queries Against Incomplete Relational Databases.
Hans-Joachim KleinPublished in: FMLDO (1998)
Keyphrases
- null values
- relational databases
- integrity constraints
- query evaluation
- relational algebra
- databases
- normal form
- database
- incomplete information
- data dependencies
- relational database systems
- relational model
- functional dependencies
- inclusion dependencies
- relational calculus
- search engine
- query processing
- user defined
- database schema
- query language
- sql queries
- relational data
- relational database management systems
- conjunctive queries
- expressive power
- object oriented
- xml databases
- retrieval strategies
- xml retrieval
- relevance judgments
- keyword queries
- test collection
- query logs
- range queries