MySQL: Illegal mix of collations I've tried using a stored procedure to create indices, and got the following error:

ERROR 1267 (HY000): Illegal mix of collations (utf8_general_ci,IMPLICIT) and 
                    (utf8_unicode_ci,IMPLICIT) for operation '='


There's no line number or any other debugging hint. 


What's the best way to debug this error?
Are there any good guidelines to avoid encoding inconsistencies?
After some trial and error, I've learned how and where to apply COLLATE:

Converted lines like:

SELECT SOMETHING
FROM SOMEWHERE
WHERE table_schema = given_database
AND   table_name   = given_table
AND   index_name   = given_index;


To:

SELECT SOMETHING
FROM SOMEWHERE
WHERE table_schema COLLATE utf8_unicode_ci = given_database
AND   table_name   COLLATE utf8_unicode_ci = given_table
AND   index_name   COLLATE utf8_unicode_ci = given_index;