In mailwizz you can create custom fields which get assigned a field_id in the database table. So in my case the customer field is called rank and the field_id = 24.
The SQL to see the values grouped would look like this.
select value, count(*) from mw_list_field_value as lfv where field_id = 24 group by value ;
The SQL to update the rank values would look like this.
update mw_list_field_value set value = 'E' where field_id = 24 and value = 'D'; update mw_list_field_value set value = 'D' where field_id = 24 and value = 'C'; update mw_list_field_value set value = 'C' where field_id = 24 and value = 'B'; update mw_list_field_value set value = 'B' where field_id = 24 and value = 'A';