Is it always necessary for each table to have a unique identifier?

It is not always necessary to have a unique identifier for each table, but in most cases, it greatly simplifies working with data.

A unique identifier (for example, a primary key) allows:

• To unambiguously identify each record.
• To ensure data integrity and correct relationships between tables.
• To simplify updating and deleting specific records.

However, there are situations where a table is a reference or journal, where a unique key is not needed, or uniqueness is ensured by a combination of several fields (composite key). For example, a settings table where uniqueness is defined by the parameter name and context.

Overall, having a unique identifier is good practice, but not a strict requirement for all tables.