Why this error: Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_bin,NONE) for operation '=', ON THIS QUERY?

Question

Query:

select *,
       (@page_path = concat(
           @page_path,
           chk_v_application_tree.alias
       )) as path
from chk_v_application_tree 

[Err] 1267 - Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_bin,NONE) for operation '='

Answer 1

Try:

select *,
       (@page_path = concat(
           CONVERT(@page_path USING utf8) COLLATE utf8_bin,
           chk_v_application_tree.alias
       )) as path
from chk_v_application_tree

As you may not mix charset encoding in an CONCAT function like CONCAT(utf8_general_ci, utf8_bin).