The objective of the thesis is the development of DesignQT, an application for the study and the teaching support in Relational Algebra that provides the theoretical basis for relational databases and query languages ​​to interact with them. The available applications mainly support the graphical creation of the models but not the representation of tables and operators to build the query trees in the context of Relational Algebra. At first instance, the tool’s purpose is to provide a design method that complies with the study and formalisms of Relational Algebra. Additionally, it aims to be an assisted guide to the in-depth study of the subject through the construction of formally correct query trees satisfying all the imposed constraints.