suresh The difference between a primary key and a unique key in a database management system:
In a database management system, the primary key and unique key serve distinct purposes. The primary key is a column or a set of columns that uniquely identifies each record in a table. It uniquely identifies a row and ensures that no two rows will have the same key value. Additionally, the primary key column cannot contain null values.
On the other hand, a unique key also ensures that each value in a column or a set of columns is unique, but unlike a primary key, it allows for one null value. A table can have multiple unique keys, but only one primary key.
In summary, the primary key is a unique identifier for a record, while a unique key ensures the uniqueness of values in a column or set of columns but allows for at least one null value.
When working with database management systems, understanding the distinction between primary and unique keys is crucial for maintaining data integrity and efficient querying processes.
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