The principle of least privilege is the most important principle to apply when granting access to an ERP system that contains a significant amount of personal data. The principle of least privilege states that users should only have the minimum level of access and permissions necessary to perform their legitimate tasks and functions, and no more. Applying the principle of least privilege helps to protect the privacy and security of the personal data in the ERP system, as it reduces the risk of unauthorized or inappropriate access, disclosure, modification, or deletion of the data. It also helps to comply with the privacy laws and regulations, such as the GDPR, that require data controllers and processors to implement appropriate technical and organizational measures to ensure a level of security appropriate to the risk.