Cayenne supports SQL functions since 4.0 but only a limited set common for all supported DBs.
There are a lot more SQL functions provided by each DB that can't be supported by Cayenne directly. So we need a way to allow calls to this functions for users.
For the Property API it can be implemented as
For the Expressions API we can use syntax like this:
This will cover almost all use cases with the exception of SQL functions with special syntax, like