Abstract: As the basic unit of data processing and concurrency control,database transaction is widely used in business logic of software applications.It is a significant method in software maintenance for monitoring internal state to derive invariants and establish corresponding data contracts based on data collected from database transactions at runtime.Currently,in the field of invariant derivation,most researches and tools are just based on deriving invariants from source code, while there is lack of researches on deriving invariants from data.To solve this problem,this paper firstly introduced an algorithm for deriving invariants in the form of algebraic equations.Moreover,a prototyping tool was designed and implemented to collect data from database transactions at runtime and derive invariants among these data.With experiments,the prototyping tool is proved to be effective both on accuracy and performance,which fills the gap of inva-riants derivation based on data.

Key words: Database transaction,Invariant derivation,Algebraic equation