Fuzzy Group By Queries via RL-Instances in Conventional RDBMS Marín Ruiz, Nicolás Sánchez Fernández, Daniel Rivas Gervilla, Gustavo smoothing methods Data analysis relational databases fuzzy systems SQL group by queries allow grouping tuples in relational databases and computing aggregated values from the obtained sets of tuples, which makes them a particularly useful tool for data analysis. In this paper, we propose a way to solve this type of queries in a fuzzy environment, using fuzzy partitions of the domain of attributes according to Ruspini. The resolution of the query is carried out through the use of RL-instances and concepts from the theory of Representations by Levels, particularly a new method to derive RL-partitions from fuzzy partitions. The approach can be easily used in conventional systems through well-known SQL patterns. 2026-02-17T09:52:12Z 2026-02-17T09:52:12Z 2025 conference output N. Marín, G. Rivas-Gervilla and D. Sánchez, "Fuzzy Group By Queries via RL-Instances in Conventional RDBMS," 2025 IEEE International Conference on Fuzzy Systems (FUZZ), Reims, France, 2025, pp. 1-6, doi: 10.1109/FUZZ62266.2025.11152119 979-8-3315-4319-8 https://hdl.handle.net/10481/111072 10.1109/FUZZ62266.2025.11152119 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional IEEE