Set-valued database publication has been increasing its importance recently due to its benefit for various applications such as marketing analysis and advertising. However, publishing a raw set-valued database may cause individual privacy breach such as the leakage of sensitive information like personal tendencies when data recipients perform data analysis. Even though imposing data anonymization methods such as suppression-based methods and random data swapping methods to such a database can successfully hide personal tendency, it induces item loss from records and causes significant distortion in record structure that degrades database utility. To avoid the problems, we proposed a method based on swapping technique where an individual's items in a record are swapped to items of the other record. Our swapping technique is distinct from existing one called random data swapping which yields much structure distortion. Even though the technique results in inaccuracy at a record level, it can preserve every single item in a database from loss. Thus, data recipients may obtain all the item information in an anonymized database. In addition, by carefully selecting a pair of records for item swapping, we can avoid excessive record structure distortion that leads to alter database content immensely. More importantly, such a strategy allows one to successfully hide personal tendency without sacrificing a lot of database utility.Future Internet 2019, 11, 138 2 of 16 of hiding personal tendency we give the following example. An internet user, Bob, accessed various websites where most of the websites that he visited can be categorized as automobile websites, and to this end we can say that Bob has a strong tendency to the automobile category. The web address that Bob accessed are collected by On-line advertisement company, says AdOn. In one day AdOn release the log of the internet users, including Bob's web access log to its collaborator company, namely AdOff. Unfortunately, an irresponsible agent who is working in AdOff knows the information about Bob's tendency by analyzing his browsing history and starts to send email spam that contains interesting information about automobiles, as well as inserting a malicious link in the email, due to his curiosity Bob may get in trouble if he clicks the malicious link.The illustration story tells us that the spammer sends email spam that is precisely related to the targeted personal tendency. However, if Bob's tendency is hidden, the spammer might fail to trap Bob, since the email spam would not be too precise to Bob's personal tendency. As a result, even if Bob receives the email he might ignore it and refrain to click a link that does not attract him.As the nature of a set-valued database where an individual is directly correlated to his/her items, accordingly, prior to publishing such a database to the public, one should consider a data anonymization process such that the personal tendency of individuals can be protected in a published database. Several data anonymization techniques...