Abstract: The invention provides a method of evaluating a query involving a relational database comprising a relational data-base management system (RDBMS), said query relating to at least one table of said relational database, said method comprising determining a table as a gateway table for evaluating said query, retrieving one or more unique identifiers of said gateway table related to one or more entries in a table to be queried, retrieving information from tables to be queried related to said retrieved unique identifiers of said gateway table, and providing a result set comprising the retrieved primary keys of the gateway table in relation to said retrieved information. The invention further provides a related data processing system and program.

Abstract: The invention provides a method of evaluating a query involving one or more relational databases, each comprising a relational database management system (RDBMS), said query relating to at least two tables of said relational database, said method comprising determining a set of tables, including the tables referred to in the query, wherein each of the tables in said set is linked to at least one other table, such that, in a graphical representation of the database wherein the tables are represented as nodes and links between the tables are represented as lines between the nodes, they form a connected graph connecting nodes corresponding to the tables referred to in the query, performing a query on said set equivalent to the initial query, wherein said step of performing said query on said set comprises performing consecutive partial queries, wherein a result of a previous query is used as input for a later query, combining the results of said partial queries to obtain a result to the initial query.