The Hierarchical Database System

In database management system, there is divided into four type that is hierarchical database, network database, relational database and object-oriented database. Each database system has difference than each of the type. And each database system have each benefit and some lacking towards each others. The most useful and quite popular use is hierarchical database.  The hierarchical database is a model which organizes data in a tree structure. There is a hierarchy of parent and child data segments. This structure implies that a record can have repeating information, generally in the child data segments. Data in a series of records, which have a set of field values attached to it. It also collects all the instances of a specific record together as a record type. These record types are the equivalent of tables in the relational model, and with the individual records being the equivalent of rows. To create links between these record types, the hierarchical model uses Parent Child Relationships. These are a 1:N mapping between record types. This is done by using trees, like set theory used in the relational model, "borrowed" from maths. For example, an organization might store information about an employee, such as name, employee number, department, salary. The organization might also store information about an employee's children, such as name and date of birth. The employee and children data forms a hierarchy, where the employee data represents the parent segment and the children data represents the child segment. If an employee has three children, then there would be three child segments associated with one employee segment. In a hierarchical database the parent-child relationship is one to many. This restricts a child segment to having only one parent segment. There is some advantages in this hierarchical database. The advantages of hierarchical database is firstly simplicity. Its  mean,  the database is based on the hierarchical structure and the relationship between the various layers is logically simple. Secondly is data security. Hierarchical model was the first database model that offered the data security that is provided by the DBMS. Next, the advantages of hierarchical database is a data integrity. It  is based on the parent child relationship and  there is always a link between the parent segment and the child segment under it. Lastly is a efficiency. It is a very efficient when the database contains a large number of 1:N  relationship and when the user require large number of transaction. and also there is some disadvantage in this database systems. The disadvantages of  hierarchical database is each child only have one parent. Beside, linkage between children are not allowed. Next, implementation complexity. Although  it is simple and easy to design, it is quite complex to implement. Then, 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 also is a disadvantages of  hierarchical database. There is a lack of structural independence because when we change the structure then it becomes compulsory to change the application too. Lastly,  operational anomalies. Its mean, hierarchical model suffers from the insert, delete and update anomalies and also retrieval operation is difficult. This is only about the hierarchical database systems. This type of database is quite useful for some organization because it really user-friendly and give many benefits.