This thesis deals with database method refactoring. The goal of theoretical part of the thesis is tothoroughly describe the principles, advantages and risks of database method refactoring. The goal ofpractical part of the thesis is to demostrate the implementation of each type of method refactoring.These goals are achieved throught detailed description of each type of database method refactoring andby demonstrating refactoring examples.First thing explained by the thesis is the term refactoring and the specifics of database refactoring andits categories. After that follows detailed description of each type of database method refactoring,where each one has detailed description of principle behind it, motivation for its use, advantages, risks...