Illegal mix of collations error in MySql

Question

Just got this answer from a previous question and it works a treat!

SELECT username, (SUM(rating)/COUNT(*)) as TheAverage, Count(*) as TheCount 
FROM ratings         


        

Answer 1

Here's how to check which columns are the wrong collation:

SELECT table_schema, table_name, column_name, character_set_name, collation_name

FROM information_schema.columns

WHERE collation_name = 'latin1_general_ci'

ORDER BY table_schema, table_name,ordinal_position; 

And here's the query to fix it:

ALTER TABLE tbl_name CONVERT TO CHARACTER SET latin1 COLLATE 'latin1_swedish_ci';

Link

Answer 2

If you want to avoid changing syntax to solve this problem, try this:

Update your MySQL to version 5.5 or greater.

This resolved the problem for me.

Answer 3

SELECT  username, AVG(rating) as TheAverage, COUNT(*) as TheCount
FROM    ratings
        WHERE month='Aug'
        AND username COLLATE latin1_general_ci IN
        (
        SELECT  username
        FROM    users
        WHERE   gender = 1
        )
GROUP BY
        username
HAVING
        TheCount > 4
ORDER BY
        TheAverage DESC, TheCount DESC;

Answer 4

You need to set 'utf8' for all parameters in each Function. It's my case:

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Answer 5

I think you should convert to utf8

--set utf8 for connection
SET collation_connection = 'utf8_general_ci'
--change CHARACTER SET of DB to utf8
ALTER DATABASE dbName CHARACTER SET utf8 COLLATE utf8_general_ci
--change CHARACTER SET of table to utf8
ALTER TABLE tableName CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci

Answer 6

Make sure your version of MySQL supports subqueries (4.1+). Next, you could try rewriting your query to something like this:

SELECT ratings.username, (SUM(rating)/COUNT(*)) as TheAverage, Count(*) as TheCount FROM ratings, users 
WHERE ratings.month='Aug' and ratings.username = users.username
AND users.gender = 1
GROUP BY ratings.username
HAVING TheCount > 4 ORDER BY TheAverage DESC, TheCount DESC