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.

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