Query language for Comm/Sci, uses Command, Follow links Dev: I DBS HW: many SW: SEED
Gerritsen, R. "HARVEST Reference Manual" International Data Base Systems Inc., June 1979 view details
Tagg, Roger M. "Interfacing a query language to a CODASYL DBMS" pp46-64 view details
HARVEST is the query language that goes with IDBS's SEED system - a portable, FORTRAN-based CODASYL DBMS that works on a variety of hardware, just as TOTAL or RAPPORT do. It attempts to offer the user an 'independent item' of data, working out the path through the database itself. However if this process proves ambiguous or impossible, the user may have to help the system by identifying which record type is to be treated as the TARGET record, ie the record type at which 'occurrences' satisfying the query should be counted. This process clearly requires some understanding of the network structure.
in ACM SIGMOD Record 13(03) April 1983 view details
Subieta, Kazimierz "Semantics of query languages for network databases"
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