A computer-implemented method of processing a query on a plurality of instances of an object of an object-oriented environment, wherein said object has a root object and a plurality of member fields, among which a plurality themselves are objects thereby being sub-objects of said root object, wherein said root object and each sub-object correspond to an entity represented by and stored in form of a table, wherein said tables are tables in accordance with a relational model of data, and wherein each of said tables corresponding to said root object or to one of said sub-objects has been sorted in accordance with the primary key of the table corresponding to said root object, said method comprising: Analyzing said query to identify those objects among said root object and said sub-objects which are necessary to execute the query, for each of the primary key values of the table corresponding to said root object: i) generating an instance of said object by populating the member fields of those objects among said root object and said sub-objects, which have been identified in said analyzing step, with the data identified by the respective primary key in their corresponding tables; ii) executing the query on the generated object instance; ii) adding the result, which has been computed by executing said query on said object instance, to a result accumulator storage, wherein said step of identifying those objects, which are necessary to execute the query, comprises identifying the member fields, which are referred to in said query; identifying the objects, which correspond to the identified member fields, as objects, which are necessary to execute said query, populating an object instance member field comprises using a pointer which points to the row or the rows of the table to be inserted into a specific object instance and writing said pointer into the object instance. i) generating an instance of said object by populating the member fields of those objects among said root object and said sub-objects, which have been identified in said analyzing step, with the data identified by the respective primary key in their corresponding tables; ii) executing the query on the generated object instance; ii) adding the result, which has been computed by executing said query on said object instance, to a result accumulator storage, wherein said step of identifying those objects, which are necessary to execute the query, comprises identifying the member fields, which are referred to in said query; identifying the objects, which correspond to the identified member fields, as objects, which are necessary to execute said query, populating an object instance member field comprises using a pointer which points to the row or the rows of the table to be inserted into a specific object instance and writing said pointer into the object instance. said step of identifying those objects, which are necessary to execute the query, comprises identifying the member fields, which are referred to in said query; identifying the objects, which correspond to the identified member fields, as objects, which are necessary to execute said query, populating an object instance member field comprises using a pointer which points to the row or the rows of the table to be inserted into a specific object instance and writing said pointer into the object instance.