Patent ID: 8296313

Claim:
A method for controlling a relational database system, being based on a set-processing query language which applies predetermined set-processing functions and assigned keywords to a query statement, comprising the steps of: analyzing a query statement consisting of keywords by applying a recursive transition network (RTN), the processing of which takes place along a given decision graph which provides for the recursive usability of the decision graph at predetermined decision positions, and by allocating process-related properties to the keywords or a group of the keywords in the order given by the statement; and converting a result of said step of analyzing a query statement into control commands, wherein the RTN is formed of independent RTN building blocks, wherein each RTN building block has an inner, directed decision graph which is defined independently from the inner, directed decision graphs of the other RTN building blocks with at least one decision position along at least one decision path, wherein the inner decision graphs of all RTN building blocks are run by means of the keywords in a selection step and all possible paths of this decision graph are followed until either no match with the respectively selected path is determined by the decision graph and the process is interrupted or the respectively chosen path is run until the end, and wherein the decision paths at least partly have a recursive call function on at least one of the decision positions through which one of the RTN building blocks is run as a result of applying the selection step to all of the RTN building blocks, so that any frequently recursively nested execution of the selection step starting from the at least one of the decision positions is made possible, and in that an access plan for the relational database system is generated from the order of the RTN building blocks and their nesting as a result of the application of the selection steps on all keywords.