what about to add a custom error message for each constraint violation
instead of default system generated

the syntax would be

... constraint <constraint_name> constraint_type errormessage 'some text'

or

... constraint <constraint_name> constraint_type exception <exception_name>

for example:

alter table TABLE1 add constraint CHECK_FILED1 check (FIELD1 > 100)
errormessage 'field must be above 100';

or

create exception TABLE1_FIELD1_ERROR '............';

alter table TABLE1 add constraint CHECK_FILED1 check (FIELD1 > 100)
exception TABLE1_FIELD1_ERROR;