What does 'Upsert' refer to in database operations?

'Upsert' refers to a specific database operation that combines the functionality of both insertion and updating. When using 'upsert', the database checks for the existence of a row based on a specified unique identifier. If the row exists, it updates that row with new information. If the row does not exist, the operation inserts a new row with the given data.

This capability is particularly useful in scenarios where it is important to ensure that data remains consistent and up-to-date without needing to perform separate operations to check for the existence of the record first. The term itself is a blend of "update" and "insert," encapsulating the dual nature of the operation.

This understanding highlights the importance of data integrity and efficiency in database management, making option B the most accurate description of what 'upsert' entails in database operations. The other options focus on different types of data manipulation and do not capture the specific dual functionality that defines 'upsert'.