Mysql – Illegal mix of collations error in MySql

collationMySQLmysql-error-1267

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 WHERE month='Aug' GROUP BY username HAVING TheCount > 4
ORDER BY TheAverage DESC, TheCount DESC

But when I stick this extra bit in it gives this error:

Documentation #1267 – Illegal mix of
collations
(latin1_swedish_ci,IMPLICIT) and
(latin1_general_ci,IMPLICIT) for
operation '='

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

The table is:

id, username, rating, month

Best Answer

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';

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Mysql – Should I use the datetime or timestamp data type in MySQL

Timestamps in MySQL are generally used to track changes to records, and are often updated every time the record is changed. If you want to store a specific value you should use a datetime field.

If you meant that you want to decide between using a UNIX timestamp or a native MySQL datetime field, go with the native format. You can do calculations within MySQL that way ("SELECT DATE_ADD(my_datetime, INTERVAL 1 DAY)") and it is simple to change the format of the value to a UNIX timestamp ("SELECT UNIX_TIMESTAMP(my_datetime)") when you query the record if you want to operate on it with PHP.

Mysql – Troubleshooting “Illegal mix of collations” error in thesql

This is generally caused by comparing two strings of incompatible collation or by attempting to select data of different collation into a combined column.

The clause COLLATE allows you to specify the collation used in the query.

For example, the following WHERE clause will always give the error you posted:

WHERE 'A' COLLATE latin1_general_ci = 'A' COLLATE latin1_general_cs

Your solution is to specify a shared collation for the two columns within the query. Here is an example that uses the COLLATE clause:

SELECT * FROM table ORDER BY key COLLATE latin1_general_ci;

Another option is to use the BINARY operator:

BINARY str is the shorthand for CAST(str AS BINARY).

Your solution might look something like this:

SELECT * FROM table WHERE BINARY a = BINARY b;

or,

SELECT * FROM table ORDER BY BINARY a;

Best Answer

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Mysql – Should I use the datetime or timestamp data type in MySQL

Mysql – Troubleshooting “Illegal mix of collations” error in thesql

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