Journal of Electronic Systems Djail boubekeur, Hidouci Walid-Khaled, Loudini Malik 6 1 2016 In wireless sensor networks, the database consists of data collected by the different network nodes. This database can be accessed by relational queries, such as: selections, projections and joins. Joins are queries that use a lot of energy, which is a determining factor for network lifetime. In this paper, a new technique for n-way join queries is suggested, using an in-network processing and adopting the filtering approach. Simulation results showed very good performances of the proposed technique compared with a central processing of those queries at the sink.