Can you explain the difference between a unique key and a primary key in Oracle?

Certainly! When it comes to Oracle databases, understanding the difference between a "unique key" and a "primary key" is crucial.

A **unique key** in Oracle is a constraint that ensures the values within a column or group of columns are unique across the entire table. This means that no two rows can have the same value for the column(s) defined as a unique key. Unlike the primary key, a unique key can have one or more columns in a table, and it allows one NULL value.

On the other hand, a **primary key** in Oracle is a special type of unique key that uniquely identifies each record in a table. It acts as the main identifier for a table and enforces entity integrity. A primary key must have a unique constraint and does not allow NULL values. Additionally, only one primary key constraint can be defined for a table.

In summary, the primary difference between a unique key and a primary key in Oracle is that while both ensure uniqueness, a primary key acts as the main identifier for a table and does not allow NULL values, whereas a unique key can have NULL values and does not serve as the main identifier.

Understanding the distinctions between a unique key and a primary key in Oracle is vital for effective data management and maintaining data integrity in your database.