A method is disclosed for computing an association rule in a database having numerical attributes and 0-1 attributes. First, a numerical attribute is divided into a plurality of intervals (or buckets), and each data set is placed into a single bucket according to the value of the numerical attribute. The number of data sets in each bucket and the number of data sets with a 0-1 attribute being 1 are counted. Second, the starting bucket of an interval to be detected is to be detected. Third, the terminating bucket corresponding to the starting bucket is detected. That is, the largest interval with a confidence equal to or larger than a predetermined value. Fourth, one of the detected pairs of starting and terminating buckets which includes the largest number of customers is the answer to this question. Finally, the required data attributes of data included in this interval is subsequently retrieved.