Databases are a key part of any Information System (IS), as they are concerned with storing and retrieving the data required by the system. Among the different types of databases, the relational ones are the most widely used. According to previous works, there are two measures that affect the complexity of relational databases, the number of foreign keys (NFK) and the depth of the referential tree (DRT). However, a new kid on the block has appeared in the last years, the energy consumption of software in general and, therefore, also in databases. Bearing this in mind, the aim of this paper is to determine whether the results about the complexity of relational databases are related to the energy consumption of the database. To do that we have measured the energy consumption required by four different relational database schemas, each one of them representing different values for NFK and DRT. Moreover, we have implemented and used the four schemas on four different database management systems. As a result, we can conclude that both measures have a noticeable impact not only on the complexity but also in the consumption of the database when querying.