Negation in Relational Keyword Search.

Keyword search in relational databases frees users from writing complicated SQL queries. However, negation is still not allowed in keyword queries, limiting its expressiveness. This work addresses the problem of supporting negation in keyword queries. Our solution considers the keyword matches and the scope of negation. This enables us to correctly translate the negation using either NOT or NOT EXISTS SQL operator, and allows us to determine the user’s search intention. We also support multiple negation and nested negation in keyword queries, further increasing the expressive ability.