Why Records of Database Are Made Unique?

By having a unique value associated with each record, individual records can be selected, updated, or deleted. Being able to uniquely identify records is so important and standard in a database system that databases allow those designing a database table to specify what column (or columns) make up the primary key.

Is used to identify the records uniquely in the database?

In a relational database, a candidate key uniquely identifies each row of data values in a database table. A candidate key comprises a single column or a set of columns in a single database table.

Why do we need unique key?

The purpose of a unique key is to make sure that information in the column for each table record is unique. When you allow the user to enter the null value. Unique key is used because it creates a non-clustered index by default. Unique key can be used when you have to keep null values in column.