In the article, the author presents the theoretical and practical aspect of the use of the two most commonly employed modes of subscribing to library collections in the form of data bases described in the Act of Public Orders. The modes in question involve: an unlimited tender bid and sole-source contract order. Moreover, the author discusses one of the ways of purchasing data bases which is employed by the Jagiellonian Library and which is not subject to the Public Orders Act; this particular method concerns orders whose total value does not exceed the sum defined by the legislator.