I am creating application for Diabetes log system. I am confused whether database in UML -Use case diagram count as actor or not ?
the application is recording the diabetes glucose reading which will be saved in firebase and it can also retrieve the readings for showing the progress in chart format.
please can someone help me?
No, databases should not be included in a Use Case Diagram of an isolated system. Databases are a static internal part of a system and do not directly take part without a front interface (i.e. your system itself).
However, if your database is an external entity i.e. it is being shared between different systems then maybe it would be wise to show it as an actor.Answer2:
That depends on what use case diagram are you working on. UML standard does not attach diagrams to levels of abstraction.
You can create use case for the behaviour of the whole product with all surrounding system and human users - from the point of view of an external user. And you can create it for better explanation of behaviour of a small sub-sub-subsystem.
In the first case even the main application won't appear as an agent or meant as a subject. In the second case, if that subsystem works with DB, DB will be an agent.
UML is a free enough standard and rarely strictly forbid something.