What is the result of merging two datasets with overlapping and unique IDs?

When merging two datasets that contain overlapping and unique IDs, the outcome is determined by the type of merge being performed. The correct answer indicates that only matching records based on IDs are retained.

In a typical scenario where you perform a merge using a common key (the ID in this case), the operation works similarly to an inner join in SQL. This means that only those records from both datasets where IDs match are included in the resulting dataset. If an ID exists in one dataset but not in the other, that record will not appear in the merged result.

This behavior is particularly important in data management as it ensures that only relevant records are analyzed together, preserving the integrity of data relationships. In a situation with overlapping IDs, one dataset's records will be combined with the matching records from the other dataset, while unique IDs—those that don’t appear in both—will be excluded from the final output.

The concept of retaining only matching records is critical in scenarios where one desires to see how two sources of information relate to each other via common identifiers, making the understanding of this merging process vital for accurate data analysis.