What type of join would you expect to use when building a parent-child hierarchy?

In the context of building a parent-child hierarchy, a self-join is the most appropriate type of join to utilize. A self-join is used when a table needs to be joined with itself to relate rows within the same table. This is particularly useful when you have hierarchical data, such as an organizational chart or a product categorization where each record (child) relates to another record (parent) within the same dataset.

When constructing a parent-child hierarchy, self-joins allow you to represent relationships between different levels of the hierarchy. For example, if you have an employees table where each employee has a manager ID pointing to another employee within the same table, using a self-join helps to connect each employee with their respective manager, thereby facilitating the creation of a complete hierarchy.

Other types of joins like temporal, relational, and dynamic joins do not serve the same purpose in this context. Temporal joins are focused on time-based data relationships, relational joins typically connect different tables, and dynamic joins are utilized for scenarios involving changing relationships that cannot be defined in advance, which do not align with the static nature of a defined parent-child hierarchy.