The metadata can be easily defined as data about data, the key about key, and information about information. This terminology of metadata which is used to represent other data set is known as metadata(Alex, 2013; Gary 2009; Jiawei, 2011). The metadata in data mining defines from the warehouse objects (OLAP). The metadata acts as a directory. This directory helps the decision support system to locate the contents of a data mining.
The keys are the attributes of a particular table and the set of attributes are used to access tuples from the table, they are also used to build a relationship between the tables. In this research paper, we are going to discuss the primary candidate key that difference between them is a great demand for information management on both primary and candidate keys uniquely identify a tuple in relation or table(Abraham, 2013; Elmasri, 2007). but the most important point that differentiates them is that there can be only one primary key in a relation. however, there can be more than one candidate key non-key attribute in a relation.
Primary Key and Candidate Key