Which type of join returns all records from both datasets, matching where possible?

Which type of join returns all records from both datasets, matching where possible?

• A. Inner Join
• B. Full Outer Join
• C. Left Outer Join
• D. Right Outer Join

Answer: (B)

A Full Outer Join is designed to return all records from both datasets being combined, where there is a match based on the specified keys. When a match exists, the data from both tables is included in the result. In cases where a match does not exist, the output will still include records from both datasets, but the fields corresponding to the dataset that lacks a match will be filled with null values. This type of join is particularly useful when you want a comprehensive view of both datasets, allowing you to see both the overlapping and non-overlapping records. It gives a complete picture of the data available in both tables, making it easier to identify gaps or unique records in each dataset. In contrast, other types of joins, such as Inner Join, Left Outer Join, and Right Outer Join, restrict the results to either matched records or a subset of records from one dataset. An Inner Join only returns rows with matches in both datasets. A Left Outer Join returns all records from the left dataset and matched records from the right dataset, while vice versa for the Right Outer Join. These limitations highlight why the Full Outer Join is the appropriate choice for retrieving all records from both datasets regardless of match.

A Full Outer Join is designed to return all records from both datasets being combined, where there is a match based on the specified keys. When a match exists, the data from both tables is included in the result. In cases where a match does not exist, the output will still include records from both datasets, but the fields corresponding to the dataset that lacks a match will be filled with null values.

This type of join is particularly useful when you want a comprehensive view of both datasets, allowing you to see both the overlapping and non-overlapping records. It gives a complete picture of the data available in both tables, making it easier to identify gaps or unique records in each dataset.

In contrast, other types of joins, such as Inner Join, Left Outer Join, and Right Outer Join, restrict the results to either matched records or a subset of records from one dataset. An Inner Join only returns rows with matches in both datasets. A Left Outer Join returns all records from the left dataset and matched records from the right dataset, while vice versa for the Right Outer Join. These limitations highlight why the Full Outer Join is the appropriate choice for retrieving all records from both datasets regardless of match.