Sweden, I assume. The personnummer (personal number) consists of the following:

- The birth date, e.g. 640823 (YYMMDD)

- The birth number, three digits. Last digit is odd for men and even for women.

- A check digit, calculated by the Luhn algorithm.

A full example: 640823-3234 -- a male born on August 23, 1964.

Assuming this is Sweden, the full database is not generally handed out, although you can call the government agency and ask them to do individual queries (e.g. if you are trying to find someone but only know their name and not their address).

However, the database can be given out in full under certain circumstances. In particular, companies which do credit checks are given realtime access to it. In maybe an unanticipated turn of events, one of the the credit check companies (Bisnode AB) then decided to sell access to it more generally, so nowadays it's fairly widely available to companies. In particular, there are a bunch of websites (hitta.se , birthday.se, ...) which let's you cross-reference name, address, and date of birth for anybody.