“In the network model, the data are represented by collections of records and relationships between data are represented by links. This structure holds for the hierarchical model as well. The only difference is that, in the hierarchical model, records are organized as collections of trees, rather than as arbitrary graphs.”(http://codex.cs.yale.edu/avi/db-book/db6/appendices-dir/e.pdf, 17-10-2014)
This database model use rules as each child has one parent and each parent can have many children nodes.
Advantages:
• Simple based on Hierarchal structure, the relationships between the layers (parents or child nodes).
• Data Security: the first database model that offered the data security that is provided by the DBMS. DBMS …show more content…
• Efficiency: It is very efficient because when the database contains a large number of 1:n relationship and when the user require large number of transaction.
• It’s very fast to access data at the top
• Large base with a proven technology.
Disadvantages:
• Implementation complexity: While it is simple and easy to design, it is quite difficult to implement.
• Database Management Problem: If you make any changes in the database structure, then you need to make changes in the entire application program that access the database.
• Lack of Structural Independence: there is lack of structural independence because when we change the structure then it becomes compulsory to change the application too.
• Operational Anomalies: This model has irregularities from the insert, delete and update, also retrieval operation can be difficult.
• Rigid rules.
• Duplicate data.
• Data can be very slow when information on the lower entities.
• Searching data is extremely …show more content…
Hierarchal database uses “each child has one parent and each parent can have many children nodes”, Network each child has many parents and each parent can have many children and Relational uses more complex method because this kind of schema uses tables and relationships between tables.
About the structure, Hierarchal schema show us data such as tree structure it’s very easy to understand while Network use a graph structure which is more challenging to comprehend and Relational uses RDBMS which as more user-friendly because the data are presenting in tables.
In relation how to handle with data, Hierarchal is easy to adding new information but is complex when we need to update or delete data. Network is easy to adding new information and it’s more complex comparing to hierarchal because their own rules, Relational is the easiest to manipulate data because uses RDBMS and it’s possible to retrieve complex data but you need to have some knowledge about SQL.
In terms of performance Hierarchal can be very slower and time-consuming when dealing with retrieving data, Network it’s a bit slower than Hierarchal because of their complexity between tables (The network model allows each record to have multiple parent and child