#Super key in dbms how to#

So, from the above table, we conclude the following set of the super keys: The EMPLOYEE_DETAIL table is given below that will help you understand better: Let's consider an EMPLOYEE_DETAIL table example where we have the following attribute:Įmp_SSN: The SSN number is stored in this field.Įmp_Id: An attribute that stores the value of the employee identification number.Įmp_name: An attribute that stores the name of the employee holding the specified employee id.Įmp_email: An attribute that stores the email id of the specified employees. Note: Two or more attributes in a table can together identify a table uniquely, so the combination of such attributes is nothing but a super key only. So, all those attributes in a table that is capable of identifying the other attributes of the table in a unique manner are all super keys. It is the superset where the candidate key is a part of the super key only.

The role of the super key is simply to identify the tuples of the specified table in the database.

#Super key in dbms how to#

Here, we will discuss about the super key, i.e., what is the role of a super key, how to use it, and will be looking at some practical examples that will help us to understand it in a better way. It means a candidate key is obtained from a super key only. Thus, a super key is the superset of a key known as a Candidate key (discussed in the next section). The word super denotes the superiority of a key. We can define a super key as a set of those keys that identify a row or a tuple uniquely.