The answerability of database queries

Phillip Ein-Dor*, Israel Spiegler

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


A conceptual model is presented of the man-machine interface in data-base environments. It is suggested that this model, entitled Query Normal Form (QNF), is a universal mediator between formal query languages and relationally structurable data bases. As such, it provides a high degree of independence of query formulation from specific data-base structures. Furthermore, it can be used to verify the syntactic and semantic validity of queries stated in formal query languages before the initiation of data-base search. The descriptive adequacy of QNF as a model of formal query languages is established, as is its relational completeness in data-base interrogation capabilities. Finally, possible errors in QNF, both syntactic and semantic, are evaluated, and this line of research is compared with that of natural language query systems.

Original languageEnglish
Pages (from-to)261-270
Number of pages10
JournalInformation Systems
Issue number3
StatePublished - 1985


  • conceptual view
  • data base queries
  • descriptive adequacy
  • formal query languages
  • man-machine interface
  • natural language queries
  • relational completeness
  • relational model
  • semantic errors
  • syntactic errors


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