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Network structure The popularity of the network data model coincided with the popularity of the hierarchical data model. Some data were more naturally modeled with more than one parent per child. The network model permitted the modeling of many-to-many relationships in data. In the year 1971, the Conference on Data Systems Languages (CODASYL) formally defined as the network model. The set construct is the basic data modeling construct in the network model. An owner record type, a set name, and a member record type together creates a set. The multiparent concept is supported by a member record type can have that role in more than one set. An owner record type can also be a member or owner in another set. The data model is a simple network, and link and intersection record types (called junction records by IDMS) may exist, as well as sets between them. Thus, the complete network of relationships is represented by several pairwise sets; in each set some (one) record type is owner (at the tail of the network arrow) and one or more record types are members (at the head of the relationship arrow). A set defines a 1:M relationship, although 1:1 is permitted. The CODASYL network model is based on mathematical set theory. Prajakta Pandit 03-14-2017 05:36 AM

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