Keyphrases
- null values
- relational databases
- relational algebra
- relational model
- query language
- databases
- sql queries
- normal form
- integrity constraints
- query evaluation
- functional dependencies
- relational database systems
- database
- containment of conjunctive queries
- aggregate functions
- relational calculus
- data model
- database design
- incomplete information
- data dependencies
- expressive power
- database schema
- relational data model
- recursive queries
- database theory
- object oriented
- database technology
- data types
- xml databases
- entity relationship
- management system
- database applications
- database queries
- transitive closure
- aggregate queries
- xml data
- complex objects
- sql server
- data integration