There are few researches on fuzzy queries of relational databases involving the fuzzy conditions or relative linguistic quantifiers in "having" clause. Methods based on fuzzy set theory to these queries were presented here. The fuzzy conditions in "having" clause were translated to general SQL queries on the basis of-cut of membership function. Therefore, the tuples can be filtered by the RDBMS, which improves the efficiency of fuzzy queries. Nonfuzzy cardinality of fuzzy set was used to evaluate the quantified "having" clause, so the computation and the result became simple.