What does a full outer join guarantee when combining two tables?

A full outer join is used in SQL to combine two tables, ensuring that all records from both tables are included in the result set, regardless of whether there is a match between the two. This means that if a matching record exists in both tables, it will be displayed, but if only one table has a matching record, that record will still appear in the results, with the non-matching side filled with NULL values.

This is particularly useful for situations where you want to compare data sets comprehensively and observe how they relate to each other, including identifying unmatched records from both tables. By providing all data from both tables, a full outer join gives a complete picture of the datasets being analyzed, making it easier to identify where there are similarities and differences between them.

Other options fail to encompass the true nature of a full outer join. For instance, the first option mentions that only shared data is included, which does not represent the comprehensive nature of this type of join. The third option focuses solely on non-matching records, overlooking the inclusion of matched records. Lastly, the last option limits the result to records from just one table, which contradicts the definition of a full outer join entirely.