Database schema, also called Entity Relationship Diagram (ERD). As the role of QA and BA, I mainly read ERD, not the creator of it. As a BA, when you receive an existing project, you usually have to review all documents at the overall level to give a look at the system as well as the estimate for the upcoming project. As QA, you should (need) know about database structure, it will help you perform more efficient testing, as mentioned here. In this article, I will describe the possible components of ERD through an example. I will also say through the method like BA, how should you write the requirement so that Dev can understand and draw an ERD as the system needs. Finally, as a QA, what basic characteristics do I need to consider.