In the broadest definition, all databases are the same in that they store data, and the data can be manipulated or called up. At the same time, there is a defining aspect of each database called the database model. The database model is the structure of the data, and the model dictates how the data interact, and how they are displayed. There are five main database models, though some database designers create hybrids of the models to suit the needs of the entity that requires the database. These five models are the flat model, hierarchical model, network model, relational model and object model.
The flat database model is the simplest of all databases. It is used when all the database values are similar, and there is only a small amount of information that needs to be stored. This schema shows all the data in a table or spreadsheet, with each row being a different record. Commonly, to keep the database secure, each row will have a different password.
Early in the development of databases, the hierarchical database model was one of the most popular, and it is still commonly used in 2011. Within this database, every record has a hierarchy, from broad records to specific ones. This database is build with a parent-child relationship, meaning a broad record — or a parent — will open up to reveal specific — child — records. The network database model is almost the same as the hierarchical model, except several parents can connect to the same child, allowing this model to make more complex interactions.
The object database model concerns itself with making tables within tables to prevent database overhead. For example, in most other database models, every record will need to be coded into the database separately. In the object model, a main table can be made and each record in that table can contain other similar records. This allows those similar records to be encapsulated separately, making organization simple to maintain.
Since its inception in the 1970s, the relational database model has been the most popular model, because of its ability to group data in ways that are easy to understand and easy to call. As the name implies, this model deals primarily with the relationship between data sets and finds commonalities between records to make it easy for administrators to call similar data. These databases also use several different tables at once, and each record can have a key that separates it and allows for relationships that are more complex.