What should you ensure when creating a relationship between fields in different tables?

When creating a relationship between fields in different tables, it is crucial to ensure that both fields have the same data type. This requirement is fundamental in database design because when establishing relationships—such as primary keys and foreign keys—it is essential that the data being compared or linked is compatible. For instance, if one field is set to be an integer and the other is a text string, the database will struggle to create a valid relationship, as it cannot meaningfully compare or link disparate data types. Ensuring that both fields share the same data type guarantees that the database can accurately process queries and maintain data integrity across the relationship.

Other options, while important in their own right for overall data management or integrity, do not specifically address the immediate requirement for establishing a valid relationship between fields. For example, backing up tables is an essential practice for data protection but does not influence the functional aspect of creating relationships. Similarly, while ensuring that there are no duplicate values can help maintain unique constraints in some scenarios, it does not pertain directly to field compatibility in establishing a relationship. Finally, the existence of related records is important for the relational integrity of the database but does not affect the initial formation of the relationship itself.