Comparing priority, weighted and queries with threshold in PFSQL

PFSQL is the query language used for querying fuzzy relational databases. One of the most recognizable features of PFSQL is the possibility to prioritize conditions. Priorities are most often confused with weights. In this paper we compare queries with prioritized conditions with queries with weighed conditions. Since PFCSP systems are the theoretical background for PFSQL and similarly WFCSP are the theoretical background for weighted queries we elaborate these two systems. Queries with thresholds are another feature of PFSQL. When a threshold is attached to a condition only the tuples that satisfy the condition with a higher value then the threshold are displayed in the result. Through examples we compare these features of PFSQL.