This article presents an empirical study of how the use of relational database access technologies in open source Java projects evolves over time. Our observations may be useful to project managers to make more informed decisions on which technologies to introduce into an existing project and when. We selected 2,457 Java projects on GitHub using the low-level JDBC technology and higher-level object relational mappings such as Hibernate XML configuration files and JPA annotations. At a coarse-grained level, we analysed the probability of introducing such technologies over time, as well as the likelihood that multiple technologies co-occur within the same project. At a fine-grained level, we analysed to which extent these different technologies are used within the same set of project files. We also explored how the introduction of a new database technology in a Java project impacts the use of existing ones. We observed that, contrary to what could have been expected, object-relational mapping technologies do not tend to replace existing ones but rather complement them.