Keyphrases
- query language
- high level
- database
- low level
- data model
- expressive power
- object oriented
- xml data
- relational algebra
- conceptual model
- semistructured data
- query evaluation
- complex objects
- programming language
- conjunctive queries
- low level features
- constraint databases
- relational calculus
- visual query language
- recursive queries
- data manipulation
- higher level
- intermediate level
- regular expressions
- source code
- databases