Stability constraints and stability normal forms for temporal relational databases

This paper presents a new dynamic dependency and a new normal form. We give the concept of the stability constraint and establish complete axioms for stability constraints. In addition, we propose a stability normal form. A temporal third normal form can be losslessly decomposed into a sequence of stability constraints. Using the decomposition, the storage space can be reduced. The stability constraints allow to fill a suitable value into a null value. Thus, this null value therefore turns into a known value. © 1999 Elsevier Science B.V. All rights reserved.