MODELS
FILE MODEL
The flat (or table) model consists of a single, two-dimensional array of data elements, where all members of a given column are assumed to be similar values, and all members of a row are assumed to be related to one another.
HIERARCHY MODEL
Data is organized into a tree-like structure, implying a single upward link in each record to describe the nesting, and a sort field to keep the records in a particular order in each same-level list. Hierarchical structures were widely used in the structure of XML documents. This structure allows one 1:N relationship between two types of data. This structure is very efficient to describe many relationships in the real world; recipes, table of contents.One limitation of the hierarchical model is its inability to efficiently represent redundancy in data.Parent–child relationship: Child may only have one parent but a parent can have multiple children. Parents and children are tied together by links called "pointers“.
NETWORK MODEL
It organizes data using two fundamental constructs, called records and sets.Records contain fields and Sets define one-to-many relationships between records.A record may be an owner in any number of sets, and a member in any number of sets.Parent–child relationship: Child can have more than one parent and a parent can also have multiple children.
