Question

Use the following data model for this question: department department id name employee employee id name employee department employee dept id employee id department id which of the following is a situation where an outer join could be useful?

a.) when a manager wants to see all employees in the company, regardless of whether they are associated with a particular department
b.) when a manager wants to see only employees that have been assigned to a department
c.) when a manager wants to see any departments that do not have employees
d.) when a manager wants to see only departments that have employees, but not departments that don't have employees

Answer 1

An outer join is useful for seeing all employees or departments with or without associations, while inner joins are for matched entities only.

Step-by-step explanation:

An outer join would be most useful in a situation where a manager wants to see all elements from one table regardless of whether there is a matching element in the other table. In the context of the data model provided, an outer join would be particularly useful in two scenarios:

• a.) When a manager wants to see all employees in the company, regardless of whether they are associated with a particular department. This could include employees that are yet to be assigned to a department or the departments are not part of the employees' records.
• c.) When a manager wants to see any departments that do not have employees. This type of outer join, specifically a left join or right join depending on the tables' position in the query, would allow the manager to identify any departments that might be understaffed or currently not in operation.

However, scenarios b.) and d.) would more likely utilize an inner join because they only require showing departments and employees where there is a match, hence the existence of a relationship between the two entities.