Returns the character set of the string argument, or NULL if the argument is NULL.
SELECT CHARSET('abc');
'utf8mb3'
SELECT CHARSET(CONVERT('abc' USING latin1));
'latin1'
SELECT CHARSET(USER());
'utf8mb3'
SELECT CHARSET('abc');
'utf8mb3'
SELECT CHARSET(CONVERT('abc' USING latin1));
'latin1'
SELECT CHARSET(USER());
'utf8mb3'