Consistent query answers on numerical databases under aggregate   constraints
  The problem of extracting consistent information from relational databases violating integrity constraints on numerical data is addressed. In particular, aggregate constraints defined as linear inequalities on aggregate-sum queries on input data are considered. The notion of repair as consistent set of updates at attribute-value level is exploited, and the characterization of several complexity issues related to repairing data and computing consistent query answers is provided. 
Sergio Flesca, Filippo Furfaro, Francesco Parisi