Illegal mix of collations: IntelliJ and UTF8mb4
When using variables inside SQL scripts within IntelliJ products (e.g. DataGrip), certain queries will not work because the encodings of the IntelliJ client and the server missmatch. This occurs for instance when you compare variables. A typical error message looks like this:
[HY000] Illegal mix of collations (utf8mb4_unicode_520_ci,IMPLICIT) \ and (utf8mb4_general_ci,IMPLICIT) for operation 'like'``` IntelliJ products do not yet support MySQL’s utf8mb4 character set encodings. The problem occurs when using variables in queries. Per default. IntelliJ uses a UTF-8 encoding for the connection. When you use utf8mb4 as the database default character set, then variables will be encoded in UTF-8 while the database content remailns in utf8mb4. It is not possible to provide the character set encodings to the IntelliJ settings, as it will refuse to connect. Check your server settings using the MySQL client:
MySQL [cropster_research]> show variables like ‘%char%'; +————————–+—————————-+ | Variable_name | Value | +————————–+—————————-+ | character_set_client | utf8mb4 | | character_set_connection | utf8mb4 | | character_set_database | utf8mb4 | | character_set_filesystem | binary | | character_set_results | utf8 | | character_set_server | utf8mb4 | | character_set_system | utf8 | | character_sets_dir | /usr/share/mysql/charsets/ | +————————–+—————————-+
This seems correct, but when you connect with the IntelliJ client, you will get wrong results when you use variables. Until the products supportutf8mb4, you would need to add the following settings to the script in order to force the right settings.
SET character_set_connection=utf8mb4; SET collation_connection=utf8mb4_unicode_520_ci;```