This week menu are about data and database. I searched about database from internet to enrich our knowledge about it. This post contained general description about various type of database from eHow. I have only built 2 type of database, hierarchical and relational model. It was at college, and until now I've only implement relational model in my job. Later, i will add several posting related with each specific type of database.
Different Types Databases
A database consists of various types of data that are organized for a number of uses. An address book is a simple example of a database, and a more elaborately designed database might hold demographic statistics used by governmental organizations or large research corporations. Different types of databases contain different types of data.
1. Hierarchical Model
The hierarchical model database consists of child and parent data elements organized into a tree structure. The only connection permitted between two data sets as that of parent and child. The problem here can be illustrated in a very literal sense; if a company created a hierarchical database listing employees and their families, one employee would be represented by one parent element and if the employee had three children, they would be represented by three parent elements (one each). This means each child is only permitted by the system to have one parent.
2. Network Model
The network model database defined in the 1971 Conference in Data Systems Languages extends upon the hierarchical database in that data sets are permitted a many-to-many relationship. This is important because in some circumstances, child elements of data may need two parent elements, such as in the previous example. The CODASYL network model database is based on mathematical set theory, and each parent element of data can be a child element in one or more sets in the database's set construct.
3. Relational Model
In a relational model database, all data and the relationships between data are organized into tables. Each table collates data and separates each unique entry into a new row. Every row contains the same associated data fields. Each data field column has it's own unique name and corresponding data type. For example in an iTunes play list, each song is placed on its own row. Data fields each occupy their own column, and all data formats are unified. The order of rows or columns is not significant.
4. Object/Relational Model
Databases constructed with the object/relation model add new capabilities to standard tabular database systems. In addition to conventional fielded data, more intricate binary media can be stored, such as images, audio, video and applets. The user can perform complex analytical and manipulative operations to convert multimedia and other composite objects encapsulated within the data structure.
Source : eHow -Jezen Thomas
