Question

A(n)_______ self join is required when a table must be joined to itself.

A. Self Join
B. Outer Join
C. Inner Join
D. Cross Join

Answer 1

A Self Join is necessary when a table needs to be joined to itself, often used to compare rows within the same table or handle hierarchical data.

Step-by-step explanation:

The answer to the question is a Self Join. A Self Join is required when a table must be joined to itself. This can be necessary in situations where a table contains hierarchical data or when you need to compare rows within the same table. For example, if you have an employees table with a column for the manager of each employee, you could use a Self Join to pair each employee with their respective manager. This type of join is actually a special case of an Inner Join, or it can be structured as an Outer Join depending on what kind of results you are trying to achieve. It's important to alias the table properly since you are referring to the same table more than once in the query.