select distinct left(author_name,2) as fl
                from lect_author inner join lect_url_author on lect_author.author_id=lect_url_author.author_id
                where author_name like 'ΦΘ%'
                order by fl asc
Illegal mix of collations (utf8mb4_general_ci,IMPLICIT) and (utf8mb3_general_ci,COERCIBLE) for operation 'like'

select SQL_CALC_FOUND_ROWS lect_author.author_id, author_name, count(distinct lect_url_author.url_id) n_books
                from lect_author
                     inner join lect_url_author
                     on lect_author.author_id=lect_url_author.author_id
                where author_name like 'ΦΘ%'
                group by lect_author.author_id
                order by author_name asc
                limit 0, 100
Illegal mix of collations (utf8mb4_general_ci,IMPLICIT) and (utf8mb3_general_ci,COERCIBLE) for operation 'like'