Abstract: In order to help the management group of a company to mine data according to different business requirements and make decisions based on the rules that come from data mined, the authors present a core algorithm, which is based on the theory of data warehouse, rough set method, etc., and then used to mine the business data. Core algorithm starts from the information table which generates from the business requirements, and then conducts the generalization of attribute, calculates the core attribute, processes attribute reducing. At last, the rules that are described by accuracy are made. It makes improvement to the 'core set' of rough set theory in the part of calculating the core attribute, and also proves its validity. Core algorithm is implemented by SQL language programming since SQL language has such advantages, as powerful function, easy to be developed, running stable. The core algorithm focuses on business goals and can be manipulated easily.