Abstract: An append-only relational database comprises a plurality of data records, in which each data record includes a plurality of fields, including a transaction time identifying the time of creation of the said record in the database, and in which each modification, which may include a logical deletion, of an existing data record creates a further data record in said database that comprises the data of the said existing data record modified to incorporate the said modification, without altering the existing data record. Methods are also described for obtaining an accurate view of such a database at any selected point in time for audit or forensic purposes, or for obtaining a most valid view, and also for adding temporality to an existing non-temporal relational database.