The data model defines the relationships between data



  1. In the hierarchical model, have strict inheritance: department - tex2html_wrap78 employees and department- tex2html_wrap78 projects
  2. network model does many:many add employees tex2html_wrap80 -projects
  3. relational deatabase has no links, but rather relationships in the data, a dereference means making a new query. This means new fields don't have to be made when things change. Easy, and flexible, but no relationship checking.

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