The DNA database was a database compiled by Prime Minister of the United Kingdom Roger ap Gwilliam in 2046 of all citizens of the United Kingdom.
During his campaign, Roger discussed his plans for compulsory DNA testing for the entire population, something that he put into effect upon being elected. The DNA database was kept in the Department of Health and was protected by top security that the Doctor had designed.
When Ruby Sunday was seeking answers about the identity of her mother, UNIT's time window showed her and the Fifteenth Doctor a video of Roger discussing his plans for the database during his campaign. The Doctor realised that Ruby's mother would be in the database if she was still alive in 2046 and he and Ruby hacked in and compared Ruby's DNA to it. Although the database quickly found a match, this was a part of a trap for Sutekh and Ruby smashed the monitor holding the answers.
Following Sutekh's defeat, Morris Gibbons and the Vlinx retrieved the DNA results at UNIT in 2024. The database identified Ruby's parents as Louise Miller and William Benjamin Garnet. (TV: Empire of Death [+]Russell T Davies, Doctor Who series 14 (BBC One and Disney+, 2024).)