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Network Database Management Systems



NETWORK DBMS

  1. Data is represented by collection of records, and relationships among data are represented by links A link is an association between precisely two records
  2. The concept of parent and child is expanded to have multiple parent-child relationships i.e. any child can be subordinate to many different parents (or nodes)
  3. Many-to-Many relationship exists
  4. An improvement over the hierarchical model ( Also called as CODASYL database structure)

let us consider the example that we consider in the HDMS topic, the structure is represented as follows:

Unlike in the hierarchical structure, CUSTOMER-NAME can directly access ACCOUNT-NO without going through LEDGER-NO. Similarly, BANK can access all its customer PHONE numbers directly

Now the pros and cons

Pros

  1. Many-to-Many relationships, which occur quite frequently in real life can be implemented easily
  2. Speed of retrieving information is significant when compared to hierarchical model due to multiple access paths

Cons:

 

  1. Application programmer must be familiar with the logical structure of the database
  2. Change in data structures results in rebuilding the database and the programs
    Complex to construct
  3. Note The hierarchical and networking structures do not meet the requirements of physical and logical data independence





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