What is the difference between database and relational database?
A database is any structured collection of data. There are several different models for structuring data, including the hierarchical model, the network model, the relational model, the object-oriented model, and others. For example, in a hierarchical data model, data are organized into a tree-like structure. The structure allows repeating information using parent/child relationships: each parent can have many children but each child only has one parent. An example of a hierarchical data model would be if an organization had records of employees in a table (entity type) called “Employees”. In the table there would be attributes/columns such as First Name, Last Name, Job Name and Wage. The company also has data about the employee’s children in a separate table called “Children” with attributes such as First Name, Last Name, and DOB. The Employee table represents a parent segment and the Children table represents a Child segment. These two segments form a hierarchy where an employee may h