Which table operation allows you to insert unique rows to a table based on an external ID?

The operation that allows you to insert unique rows to a table based on an external ID is known as an Upsert. This operation is particularly useful when you want to either insert a new record if it does not already exist or update the existing record if it does.

By utilizing the external ID as a key reference, Upsert efficiently checks for the presence of a row in the table and ensures that any new data is added appropriately without creating duplicates. This capability is especially beneficial in scenarios where data integrity is crucial, as it maintains a unique set of entries based on the defined external identifier.

The uniqueness aspect tied to external IDs is significant; it allows the system to recognize whether the data corresponds to a new or existing entry and handle it accordingly, leading to better data management and operational efficiency.