Judgment of the Court (First Chamber) of 20 October 2022.#Digi Távközlési és Szolgáltató Kft. v Nemzeti Adatvédelmi és Információszabadság Hatóság.#Request for a preliminary ruling from the Fővárosi Törvényszék.#Reference for a preliminary ruling – Protection of natural persons with regard to the processing of personal data – Regulation (EU) 2016/679 – Article 5(1)(b) and (e) – Principle of ‘purpose limitation’ – Principle of ‘storage limitation’ – Creation, from an existing database, of a database to carry out tests and correct errors – Further processing of the data – Compatibility of the further processing of those data with the purposes of the initial collection – Retention period in the light of those purposes.#Case C-77/21.