The Ready-to-Drink market in Taiwan is too competitive for one company to stand out. Adding to the diversity of the retail channel is the fact that the drink manufacturers want to outperform each other in such a competitive market. The development of database marketing has been implemented over decades, there are many ways how retailer and manufacturer can construct their own database and use different ways to apply databases to the marketing field. This study uses the customer activity index as a model to evaluate the database from a supermarket from 2009 to 2010. The research focuses on the “Ready-to-Drink” category including tea, spirits, juice etc. The research wants to understand the customer purchasing behaviour and develop a marketing strategy for the retail channels and manufacturers by constructing the calories and caffeine data, adding it to the original database and analyzing it altogether.