Hello Thomas,
using a constant defined in the ABAP code of the AMDP class is not possible within an AMDP method. The only way to be able to use it is to pass it to the AMDP method as parameter.
The reason is that in the generated database procedure the constant defined in the ABAP code cannot be accessed.
But of course you can define the constant in the AMDP method itself using the SQLScript syntax:
DECLARE lc_yes CONSTANT nvarchar(3) := 'YES';
This has to be done unfortunately in each method you need it, cause there is not enclosing scope for several procedures.
Regards,
Florian