In order to make more flexible database access the query language SQLf has been previously proposed. One of the SQLf features is the use of Fuzzy Quantifiers in Having Clause. For this kind of query, three evaluation mechanisms have been proposed: the Naïve, the Sugeno Integral Heuristics based and the Alfa-cut Derivation based. We present in this paper a formal performance study of these three mechanisms. This study has been made using a SQLf prototype build on top of a RDBMS.