Publisher Summary Data rules are specific statements that define conditions that should be true all of the time. A data rule can involve a single column, multiple columns in the same table, or columns that cross over multiple tables. However, they always involve relationships between multiple values. Rules can also be restricted to the data of a single business object or involve data that encompasses sets of business objects. This chapter attempts to simplify the analysis process by first considering only data rules that fall within the analysis of a single business object. Data rule analysis can lead to paralysis through analysis. An overly zealous analyst can dream up countless rules that can be tested. A good data profiling analyst can reach a balance between too many rules and not enough rules. Data rule analysis is an area that is ignored too often. The problem is that data quality assessment is sometimes considered the role of business analysts. Many business analysts do not have the education or experience to be effective at doing this. However, rules are semantically based that means that the business analyst is the only realistic expert in identifying and expressing them. The technical person who is adept at SQL in all likelihood does not understand the business side.