In which case would you use a FULL OUTER JOIN?
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Both tables have NULL values.
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You want all matched data from both tables.
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You want all unmatched data from both tables.
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You want all unmatched data from one table.
A FULL OUTER JOIN returns all rows when there is a match in either left or right table records. It is specifically used to ensure that unmatched data from both tables is included in the result set.
To answer this question, you need to understand the concept of JOINs in SQL.
A FULL OUTER JOIN returns all rows from both tables, including unmatched rows from both tables. It combines the results of a LEFT OUTER JOIN and a RIGHT OUTER JOIN.
Let's go through each option to understand why it is correct or incorrect:
Option A) Both tables have NULL values - This option is not a specific condition for using a FULL OUTER JOIN. NULL values in both tables can exist regardless of the type of JOIN used.
Option B) You want all matched data from both tables - This option is not correct because a FULL OUTER JOIN returns all data from both tables, including unmatched data.
Option C) You want all unmatched data from both tables - This option is correct because a FULL OUTER JOIN returns all rows from both tables, including unmatched rows from both tables.
Option D) You want all unmatched data from one table - This option is not correct because a FULL OUTER JOIN returns all unmatched data from both tables, not just one.
The correct answer is C. A FULL OUTER JOIN is used when you want to retrieve all unmatched data from both tables.