The emerging of ubiquitous computing technologies in recent years has given rise to an increasing interest in techniques for incorporating preference and context awareness in database systems. In an ubiquitous computing scenario users access to databases will not occur at a unique context, and consequently their expectation when querying data will vary according to a multitude of relevant information including location, time and surrounding influences.

In this article is presented the CPrefSQL-Tool, a web tool allowing to execute queries and filter the results according to the user contextual preferences. Some of the functionalities of the CPrefSQL-Tool are:
(1) queries may be specified either by using standard SQL commands or by using CPrefSQL, an extension of SQL with specific operators for computing the top K and the most preferred tuples according to a set of contextual preference rules;
(2) preference rules can be specified in a more intuitive way;
(3) queries are executed by using the CPrefSQL query processor;
(4) the filtered results of a query execution are traceable and explained on user demand.