The present invention relates to recommendation of items to a user for providing items more satisfying a user's request on the basis of new association. The present invention provides a data display server connected to a user terminal, which includes a posting database for storing posting data posted through the user terminal, a reference data base for storing reference data, relational metadata generating means which generates relational metadata making association between two pieces of reference data, and a relational database for storing the relational metadata. According to the arrangement, tight linking between reference data is made possible so that items more suitable for a user's preference can be recommended.