Question

RIGHT OUTER JOIN keeps tuples in the result from r2, even if there is no join partner in r1 (left relation): all units of study will be listed even if they have no student enrolled. When there is no join partner for some subject, it is still in the result, but with a NULL studentId.

Option 1: INNER JOIN
Option 2: LEFT OUTER JOIN
Option 3: RIGHT OUTER JOIN
Option 4: FULL OUTER JOIN

Answer 1

The question asks about a SQL operation that ensures all records from a right table are included in the results. The correct answer is the RIGHT OUTER JOIN, which returns all units of study even if no students are enrolled.

Step-by-step explanation:

The question pertains to SQL JOIN operations, specifically the RIGHT OUTER JOIN. This type of join ensures that all records from the right table (r2 in this case) are included in the result set, and when there is no matching record in the left table (r1), the result is filled with NULL for the columns of the left table. Therefore, even if a unit of study has no students enrolled in it, it will still appear in the result set with a NULL studentId.

The correct answer to which JOIN operation includes all units of study regardless of whether they have a matching student enrolled is Option 3: RIGHT OUTER JOIN.