When you run a query against a MySQL database, MySQL uses a bunch of system variables to determine which character set and collation to use whenever queries are run. If the client uses a different character set to the server, then MySQL can translate it into an appropriate character set and collation.
When sending the query results back to the client, MySQL can translate these results back to a different character set altogether if required. MySQL uses system variables to determine which character sets and collations to use at each of these steps.
The following singles out the connection collation:
SELECT @@collation_connection;
Example result:
+------------------------+ | @@collation_connection | +------------------------+ | utf8mb4_0900_ai_ci | +------------------------+
Using the SHOW VARIABLES Statement
Another way to retrieve the collation_connection system variable is to use the SHOW VARIABLES statement to return various collation-related system variables. The easiest way to do this is to use the LIKE clause to narrow it down to only variables that begin with collation. Like this:
SHOW VARIABLES LIKE 'collation%';
This returns the collation for the server, connection, and database. Like this:
+----------------------+--------------------+ | Variable_name | Value | +----------------------+--------------------+ | collation_connection | utf8mb4_0900_ai_ci | | collation_database | utf8_general_ci | | collation_server | utf8mb4_0900_ai_ci | +----------------------+--------------------+
You can also return all character set system variables with the following query:
SHOW VARIABLES LIKE 'character_set%';
Example result:
+--------------------------+----------------------------------+ | Variable_name | Value | +--------------------------+----------------------------------+ | character_set_client | utf8mb4 | | character_set_connection | utf8mb4 | | character_set_database | utf8 | | character_set_filesystem | binary | | character_set_results | utf8mb4 | | character_set_server | utf8mb4 | | character_set_system | utf8 | | character_sets_dir | /usr/local/mysql/share/charsets/ | +--------------------------+----------------------------------+
Also see: