Patent ID: 7774337

Claim:
A method for controlling a relational database system, comprising the steps of: analyzing a query statement consisting of keywords by applying a recursive transition network (RTN) 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, wherein, in a conversion step prior to the execution of the selection steps each RTN building block is allocated either to a first or a second generic group, wherein the RTN building blocks beginning with text, symbol, variable or number are allocated to the first generic group and converted in such a way that the decision positions which include a recursive query function the selection step of which is applied to all RTN building blocks, are limited to the extent that the selection step can only be applied to the RTN building block of the first generic group, wherein the RTN building blocks beginning with a recursive query function are allocated to the second generic group and converted in such a way that the first decision position is removed, and decision positions which include a recursive query function the selection step of which is applied to all RTN building blocks, are limited to the extent that the selection step is only applied to the RTN building blocks of the first generic group, and wherein all RTN building blocks of the first generic group and those RTN building blocks of the second generic group ending with a text, symbol, variable or number at the last decision position are appended an optionally executable decision position at the last position where the selection step is only applied to the RTN building blocks of the second generic group.