alter table items rename column params to zbx_old_tmp;
alter table items add params nvarchar2(4000) default '';
update items set params=zbx_old_tmp;
alter table items drop column zbx_old_tmp;

alter table items rename column description to zbx_old_tmp;
alter table items add description nvarchar2(4000) default '';
update items set description=zbx_old_tmp;
alter table items drop column zbx_old_tmp;

alter table items rename column posts to zbx_old_tmp;
alter table items add posts nvarchar2(4000) default '';
update items set posts=zbx_old_tmp;
alter table items drop column zbx_old_tmp;

alter table items rename column headers to zbx_old_tmp;
alter table items add headers nvarchar2(4000) default '';
update items set headers=zbx_old_tmp;
alter table items drop column zbx_old_tmp;

alter table item_preproc rename column params to zbx_old_tmp;
alter table item_preproc add params nvarchar2(4000) default '';
update item_preproc set params=zbx_old_tmp;
alter table item_preproc drop column zbx_old_tmp;
