Here are some key characteristics of the Network Data Model:
1. Graph Structure: Data is organized as a graph, where entities (nodes) are connected by relationships (edges). Unlike the hierarchical model, where each child has only one parent, in the network model, a child entity can have multiple parent entities.
2. Records and Sets: In the network model, entities are called records, and relationships between records are called sets. Records are connected through sets, and a record can participate in multiple sets.
3. Access Paths: Data access in the network model is facilitated through predefined access paths, known as navigational access. Users traverse the network by following pointers from one record to another.
4. Schema Flexibility: Compared to the hierarchical model, the network model offers more flexibility in representing complex relationships. It allows many-to-many relationships between records, which can be more reflective of real-world scenarios.
5. Efficient Queries: The network model enables efficient querying by providing direct access paths to records. However, the user must know the structure of the database and the access paths to retrieve the desired information efficiently.
6. Examples: Some examples of database systems that implemented the network model include IDMS (Integrated Database Management System) and DMS-1100.
7. Complexity: While the network model provides more flexibility compared to the hierarchical model, it can also introduce complexity, both in terms of database design and querying. Maintaining the integrity of data and managing relationships can be challenging in complex networks.
Despite its advantages, the network model eventually gave way to the relational model, which offered simpler querying mechanisms and a more intuitive structure. However, the network model still has niche applications, particularly in legacy systems where it continues to be used.
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