" The circle data bank modelling was created by Charles Bachman inside 1969 just as one enlargement with the old data source product, the actual hierarchal data bank model. As the hierarchal data source model had been very fault, Bachman thought i would create a data source that may be exactly like the hierarchical data bank but a lot more freedom and fewer non-payments. The original in addition to active hierarchic data source has one particular owner report joined strictly to 1 associate file, developing a ladder impact of which qualified this database to uncover relationships outside of it's family. "
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"In this model a hierarchical relationship between two record types (representing real-world entities) is established by the set construct. A set consists of circular linked lists where one record type, the set owner or parent, appears once in each circle, and a second record type, the subordinate or child, may appear multiple times in each circle. In this way a hierarchy may be established between any two record types, e.g., type A is the owner of B. At the same time another set may be defined where B is the owner of A. Thus all the sets comprise a general directed graph (ownership defines a direction), ornetwork construct. Access to records is either sequential (usually in each record type) or by navigation in the circular linked lists. Source: http://in.docsity.com/en-docs/Database_Management_System-Introduction_to_Computing-Handout_"
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