Network model database charles (1 résultats)
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Taschenbuch. Etat : Neu. nach der Bestellung gedruckt Neuware - Printed after ordering - Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The network model is a database model conceived as a flexible way of representing objects and their relationships…. Its distinguishing feature is that the schema, viewed as a graph in which object types are nodes and relationship types are arcs, is not restricted to being a hierarchy or lattice.Where the hierarchical model structures data as a tree of records, with each record having one parent record and many children, the network model allows each record to have multiple parent and child records, forming a generalized graph structure. This property applies at two levels: the schema is a generalized graph of record types connected by relationship types (called 'set types' in CODASYL), and the database itself is a generalized graph of record occurrences connected by relationships (CODASYL 'sets'). Cycles are permitted at both levels.
