ttrss_ynh/source/schema/versions/mysql/32.sql

alter table ttrss_prefs add column access_level integer;
update ttrss_prefs set access_level = 0;
alter table ttrss_prefs change access_level access_level integer not null;
alter table ttrss_prefs alter column access_level set default 0;

update ttrss_version set schema_version = 32;