1. A method for performing queries on a search engine, based on input from a user, the method comprising: retrieving database entries from one or more relational databases; flattening the one or more relational databases with a plurality of the database entries; indexing the plurality of flattened database entries to form a full-text search engine index; prompting the user to enter an input; continuously monitoring the user input; each time an input is entered by the user, processing the user input by: computing a set of non-null partial queries in response to the input entered by the user, the non-null partial queries each being both valid on the one or more relational databases and having matching, instantiated records on the one or more relational databases thereby always resulting in non-null responses; associating a structured item to each non-null partial query; allowing the user to select one of the structured items; if the user selects one of the structured items, replacing the user input by the nonnull partial query associated to the selected structured item; when the user validates the input, executing the input as a query; and providing documents to the user corresponding to the executed query.