Prime Attribute in DBMS

Prime Attribute in DBMS

Prime Attribute In DBMS

Prime Attribute in DBMS

Prime Attribute in DBMS

Prime Attribute in DBMS


Prime Attribute in DBMS


A database is a collection of information (Data) in a Database management system. It’s like a proper organized library where we keep all the important data that any organization needs. 

Anyone can use a database to store any kind of information, like medical records, customer information, product information, financial information and so on.

You must clarify various database concepts to understand databases and Database Management Systems (DBMS). One of the most important concept is “Prime Attributes in DBMS.” 

In this blog, we’ll explain what prime attributes are, why they are important, and how they work in the backend database management system.

What is a Prime Attribute in DBMS?

Prime attributes in a database management system (DBMS) are the attributes that are part of any candidate key, or, you can say, primary key or unique key.

A candidate key (unique key) is a set of attributes that uniquely identify each tuple (row) in a table in a DBMS.

In other words, a prime attribute is an attribute that can be used to uniquely identify a record in a table.

To have a clear understanding of Prime Attributes in DBMS you have to understand these four basic concepts in DBMS –  

  1. Relation
  2. Attributes
  3. Candidate Key
  4. Prime Attribute

A relation is a set of tuples (rows), where each tuple consists of a set of values for a set of attributes (columns).

 An attribute is a property of a tuple. For example, the attributes of a customer relationship might include Customer ID, Name, and Address.

 A candidate key is a set of attributes that uniquely identify each tuple in a relation.


Student IDFirst NameDate of Birth


“Student ID” is a prime attribute because it uniquely identifies each student. As you can see in Table No two students have the same “Student ID.”

“First Name,” “Date of Birth” are non-prime attributes. They provide additional information about each student but are not used for unique identification.

 Hope you get a clear understanding that the column (Attribute) that has been uniquely identified (student ID) is called a prime attribute in DBMS.

Also Read: Generalization In DBMS

What is Prime Attribute and Non Prime Attribute In DBMS?

Prime Attribute:

Attributes that form a candidate key of a relation, i.e. attributes of Student ID, are called prime attributes. And rest of the attributes of the relation are non prime.

For Example:

Student IDFirst NameDate of BirthDepartment
01Swati2005-03-15  Sales
02Priya2006-07-20  Marketing
03Sonal2005-11-10  IT

for the relation {Student ID, First Name, Data of Birth, Department}

{Student ID} is a candidate key. It means that Student ID is a prime attribute and  First Name,  Data of Birth and Department are non prime attributes.

Non Prime Attribute:

A non-prime attribute is an attribute within a table that is not part of the primary key (Unique Key) and does not contribute to the unique identification of rows. 

Non-prime attributes provide additional information about the data but are not used for the primary purpose of uniquely distinguishing rows.

“First Name”, “Data Of Birth”, and “Department” are Non-Prime Attributes.

These non-prime attributes provide additional details about each employee but are not used for uniquely identifying employees. 

Also Read: Order of Execution In SQL

Difference Between Prime and Non-Prime Attribute In DBMS

Prime AttributeNon-Prime Attribute
DefinitionPrime attributes are attributes that are part of a candidate key (Unique Key). Non-prime attributes are attributes that are not part of any candidate key (Unique Key).
UniquenessPrime attributes always have unique values within a relation such as student ID or Employee ID.Non-prime attributes may have duplicate values within a relation.
Role in Identifying TuplesPrime attributes play a very important role in uniquely identifying tuples (Rows) in a relation.Non-prime attributes do not contribute to the uniqueness of tuples (Rows) and are used for additional information.
Inclusion in KeyPrime attributes are included in the primary key or a candidate key in DBMS.Non-prime attributes are not included in any key in DBMS.
ExampleConsider a “Students” relation with attributes: StudentID (Prime), First Name (Non-Prime), and Date Of Birth (Non-Prime).In the “Students” example,  First Nam, Date Of Birth, and Department are non-prime attributes as they are not part of the primary key (StudentID).


  • First and most important point you need to keep in mind that  Prime attributes in DBMS are integral for data integrity and uniqueness.
  • They are typically part of a candidate key or the primary key, facilitating record identification.
  • Prime attributes in DBMS are crucial for ensuring data rules are followed and for keeping the data accurate.
  • It’s very important to grasp their importance for creating well-structured databases.

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What is the difference between Primary key and prime attribute?

A primary key (Unique Key) is a specific attribute or set of attributes (columns) used to uniquely identify each record in a database table. 

On the other hand, prime attribute is any attribute that, including those in the primary key, helps make each record unique.

What is the Primary Key in DBMS?

A primary key in a database management system (DBMS) is a unique identifier for each record in a table. It keeps data accurate and also helps to quickly find and connect information in two or more tables.




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