CQLF(ID:5596/cql003)

Networked query lagnuage 

Networked query lagnuage
References:
  • Manola, F., and Pirotte, A. "CQLF - A query language for CODASYL-type databases" view details
          in Proceedings of the 1982 ACM SIGMOD International Conference on Management of Data (Orlando, Florida, June 1982) view details
  • Tagg, Roger M. "Interfacing a query language to a CODASYL DBMS" pp46-64 view details Extract: CQLF
    CQLF (CODASYL Query Language Flat) is a new approach commissioned by the US National Bureau of Standards from the Computer Corporation of America (CCA), but it is not yet a product which is on the market. CQLF aims to bring a relational style to the query language. However, it is not relational in the sense of restricting user views to flat files: instead the relational calculus syntax has been extended to include operations involving sets. User views - which are effectively subschema networks - are derived from each other in a 'closed' system as with normal relational theory. The user therefore has to be aware of the network structure, and he uses this in a syntax which is designed to be similar to IBM's SQL.
          in ACM SIGMOD Record 13(03) April 1983 view details
  • Subieta, Kazimierz "Semantics of query languages for network databases" view details Abstract: Semantics determines the meaning of language constructs; hence it says much more than syntax does about implementing the language. The main purpose of this paper is a formal presentation of the meaning of basic language constructs employed in many database languages (sublanguages). Therefore, stylized query languages SSL (Sample Selection Language) and J (Joins) are introduced, wherein most of the typical entries present in other query languages are collected. The semantics of SSL and J are defined by means of the denotational method and explained informally. In SSL and J, four types of expressions are introduced: a selector (denotes a set of addresses), a term (denotes a set of values), a formula (denotes a truth value), and a join (denotes a set of n-tuples of addresses or values). In many cases alternative semantics are given and discussed. In order to obtain more general properties of the proposed languages, a new database access model is introduced, intended to be a tool for the description of the logical access paths to data. In particular, the access paths of the network and relational models can be described. SSL and J expressions may be addressed to both data structures. In the case of the relational model, expressions of J are similar to SQL or QUEL statements. Thus J may be considered a generalization of relational query languages for the network model. Finally, a programming language, based on SSL and J, is outlined, and the issues of SSL and J implementation are considered.
          in Transactions on Data Systems 10(3) Sept 1985 view details