How to Resolve the \'Illegal Mix of Collations\' Error in MySQL?

Trouble with "Illegal Mix of Collations" Error in MySql

Encountering the "Illegal mix of collations" error while executing a query can be frustrating. To resolve this issue, follow these steps:

Check Collations

First, identify the columns with incompatible collations. Run the following query:

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;

Fix Collation Inconsistencies

Once you have identified the offending columns, adjust their collations to match the required collation using the following query:

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

Replace "tbl_name" with the name of the table with the collation inconsistencies.

Example

Applying these steps to the example query provided will resolve the problem:

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

Cautions

• Converting character sets and collations can lead to data loss.
• Always back up your database before making such changes.
• Consult MySQL documentation for more detailed information on collations and character sets.

The above is the detailed content of How to Resolve the \'Illegal Mix of Collations\' Error in MySQL?. For more information, please follow other related articles on the PHP Chinese website!