Advantages of Unique Key

What is a Unique Key?

Let’s consider one example of books in the library. In the library, each book has a unique identification number called ISBN(International Standard Book Number). Just like how each book in the library has its own ISBN which ensures that no two books are similar. In the same way in the database of customers, everyone has their unique email id so from that we can get to know about that customer in detail. So these examples illustrate the concept of unique identification in a database system. So ISBN for the book and email ID for a customer here work as a unique key....

Advantages of Unique Key

As we have discussed above, a unique key is used to remove duplicity in the table. A unique key helps to maintain the data integrity of the database by ensuring that no two records have the sane identifier, hence preventing inconsistencies and errors. It is also used as a primary key or foreign key in relational databases to establish relationships between tables, ensuring accuracy and consistency across related tables. It is automatically indexed in most DBMS implementations, which can improve query performance by providing faster searches and retrieval of data....

Difference Between Primary Key and Unique Key

Primary Key Unique Key A primary key cannot have a NULL value. Unique keys can have one NULL value. The table can have only one primary key. The table can have more than one unique key. Any change in primary key value may necessitate updates in related tables to maintain referential integrity. A unique key can be updated or deleted, it doesn’t affect the table’s integrity constraints. In some databases, the primary key can generate a clustered index by default. In some databases, a unique key can generate a non-clustered index by default....

Syntax For Creating and Deleting Unique Key

Unique Key for Creation...

Indexing and Performance

When you create unique key in database, it creates an index for columns involved automatically. So in a book index is present which helps you quickly find the information you wanted in book. Similarly in a database the index helps speed up searches for data, making it faster to retrieve information from the table. So by having unique keys you’re not only ensuring that your data is unique but also improving the performance of your database queries....

Frequently Asked Questions on Unique Key – FAQs

What is unique key in DBMS ?...