@Override
    public String toDatabaseType(Boolean value) {
        if (value == null) {
            return null;
        } else {
            return value ? "yes" : "no";
        }
    }
@author  Maria Sparenberg
@author  Patrick Hobusch
runtime-parent/runtime-typemapper/src/main/java/com/speedment/runtime/typemapper/string/YesNoStringToBooleanMapper.java