I looked at the ER diagrams that PlantUML can generate, but this kind of symbols are not familiar to me when I'm referring to ER diagrams.
Is it possible to have the classical symbols like the following image?
Thanks in advance
Not quite matching, but you can use sprites to embed any image you want, so if this doesn't fit the bill I would look into the sprites functionality.
Just to answer rapidly,
For string formatting you can see the Creole page:
With that we can see your expected result: