Abstract:Inconsistent data is confusing and conflicting. Computing credible query answers over such data is significant. However, previous related works lose information. The approach of annotation based query answer (AQA) introduces confidence annotation to differ consistently and inconsistently in attribute value. Thus, a credible query answer can be computed and information loss can also be avoided. This is limited, however, in functional dependencies. This paper extends the approach to applications where multi constraints are involved, and no attribute is definitely credible. This paper redefines its representing model and query algebra, discusses the rules for calculating valid implied constraints of the above types on query result for any query algebra, proposes a cost based heuristic algorithm to repair, and annotates the initial database. The experiments show that time performance of extended AQA is almost similar to that of SQL for any query without join, and close to SQL for join queries after optimization, but it doesn’t loss information.