Illegal mix of collations for operation 'UNION'

Before:

select '[O]',p.project_id, p.name, c.name from project_001 p inner join city c ON p.id_district = c.id
where c.name like '%Bắc Từ Liêm%'

UNION

select '[X]', id, name, district from project_002 where district like '%Bắc Từ Liêm%';


After:

select '[O]',p.project_id, p.name, c.name COLLATE utf8_general_ci from project_001 p inner join city c ON p.id_district = c.id
where c.name like '%Bắc Từ Liêm%'

UNION

select '[X]', id, name, district from project_002 where district like '%Bắc Từ Liêm%';