1. A method for performing a database query in a relational database, the database query being carried out by a database engine and being based on user-defined search criteria, which comprises the steps of: retrieving a number N of properties of a record within a main database table, the number N being higher than zero; creating a search criteria option for each of the N properties; creating a search criteria table for each of the search criteria options; creating an index for each of the search criteria tables; and performing the database query based on a user-defined combination of a plurality of the search criteria options.