Key Takeaways:

  • Super keys in DBMS are collections of properties that uniquely identify tuples in a relational database table.
  • Super keys ensure data originality, aid in selection and security, validate references, and facilitate indexing.
  • In a table storing order information, properties like order_id, customer_id, and product_id together constitute a super key.
  • While super keys encompass multiple attributes, candidate keys are individual attributes used for identifying table entries.

What Is A Super Key In DBMS?

Super keys are collections of one or more properties (columns) in database management systems that allow a tuple (row) in a relation (table) to be distinctly identified. Unlike candidate or primary keys, super keys have a wider definition. Even if a tuple has more properties than are required to identify it uniquely, it may still be uniquely identified by practically any number of properties.

A super key in DBMS is a broader phrase, whereas prospective keys and main keys are more particular ideas.

Role Of A Super Key

In a relational database, a super key's functionality is to distinctly identify tuples (rows) inside a relation (table). Essentially, a super key's job consists of the following:

  1. Originality- A super key needs to ensure that every value conjunction it embodies is distinct in each of the sets in the relation. This distinguishing feature is required for proper data recovery and processing.
  2. Selection- One way to locate certain tuples in the record set is to use the super key. It enables users to identify and find certain records using the outcomes of the properties that make up the super key and the database management system.
  3. Security Of Data- Because they make it possible for each tuple to be securely identifiable, super keys are essential for preserving data consistency. This aids in preventing inconsistent data and redundant entries in the database.
  4. Validity Of Reference- Super keys are frequently used to compare table-to-table interactions. A super key from one table could be utilized as a foreign key in another to preserve the reliability and confidentiality of references throughout linked tables.
  5. Indexing- Table rankings, which may greatly enhance the speed of obtaining information operations, are frequently made using super keys. A more effective database system locator for certain tuples is indexing.

Examples Of Super Key in DBMS

Below is an explanation of Super Key in DBMS with an example. Consider a table storing order information

























In this case, all three characteristics, order_id, customer_id, and product_id, constitute a superkey. This is because the order ID, customer ID, and product ID combined securely recognize every order.

Superkeys can be created based on the distinct properties of information being preserved, as these examples show. For the purpose of creating and managing dependable and effective databases, it is essential to comprehend superkeys.

Difference Between Super Key And Candidate Key

Super Key

Candidate Key 

A selected group of the candidate keys in a database is called a super key.

A candidate key is one of the attributes that is utilized for identifying each table entry.

A material, or a collection of many attributes, makes up the Super Key.

A candidate key appears in each candidate key table with exactly one non-null item. 

A super key in DBMS is made up of numerous columns, all of which must be specified in order to combine multiple tables.

Each entry in a relational database record is uniquely identified by an individual identifier, a candidate key.

When creating a super key, all of the attributes should be chosen in order to combine two separate tables.

Each entry in a relational database table is identified individually by an identifier known as a candidate key.

Any variable not inferior to a foreign key in a distinct table is referred to as a super key.

An element of the composite main key may consist of a traditional candidate key. 

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Super keys serve as quiet protectors of data integrity in the realm of databases. A world of effective searching, trustworthy data tampering, and solid database architecture is made possible by these sets of characteristics, which function like prints for any record and provide a distinctive identity.

Super keys become progressively more important as databases get more complicated and data consistency becomes more and more important. Their fundamental properties that reduce reliability enhance performance and streamline development, making them the foundation of reliable and effective databases.

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If you have any questions or queries, feel free to post them in the comments section below. Our team will get back to you at the earliest.


1. Can A Super Key Have Duplicate Values?

Yes. In a single table or property, super keys contain identical values. A super key must meet originality criteria that apply to the key's attribute arrangement rather than any one of its constituent values.

2. Can A Table Have Multiple Super Keys?

Yes, many super keys can exist in a table. In reality, it is not uncommon for a set of data to have multiple sets of characteristics that collectively allow every pair of tuples in the table to be uniquely identified. A super key is any combination of these qualities.

3. How Can I Determine The Super Key For A Specific Table?

A table may include more than one super key; nevertheless, for best results, the minimum key should be used as the main key.

Here are the main points:

  • Inspection: Examine individual qualities and their combinations for redundancy.
  • Closure: To find candidate keys and deduce super keys, use a method that involves mathematics.
  • Tools: Make use of computer programs that can recognize super keys automatically.
  • Domain Expertise: Make use of your comprehension of the information and its practical implications.
  • Documentation: For observations, review domain-driven information and protocol specifications.
  • Verification: Whenever possible, compare the super keys you've discovered with the real data.

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