Keyphrases
- relational databases
- database
- high level query language
- query processing
- relational database systems
- null values
- query language
- relational database management systems
- databases
- query evaluation
- relational tables
- object oriented
- normal form
- database queries
- data sources
- boolean queries
- data dependencies
- response time
- efficient processing
- web search engines
- user queries
- relational model
- sql queries
- xml databases
- complex queries
- range queries
- xml data
- keyword search
- retrieval systems
- constraint databases
- incomplete information
- query rewriting
- query logs
- search queries
- inverted index
- statistical databases
- data management