Keyphrases
- relational calculus
- relational algebra
- expressive power
- query language
- complex objects
- relational model
- arithmetic constraints
- normal form
- relational data model
- first order logic
- transitive closure
- relational databases
- database query languages
- data model
- relational database systems
- incomplete information
- database
- query processing
- natural language
- data mining
- databases