[NATIONAL] CHAR[(M)] [CHARACTER SET charset_name] [COLLATE
collation_name]

A fixed-length string that is always right-padded with spaces to the
specified length when stored. M represents the column length in
characters. The range of M is 0 to 255. If M is omitted, the length is
1.

*Note*:

Trailing spaces are removed when CHAR values are retrieved unless the
PAD_CHAR_TO_FULL_LENGTH SQL mode is enabled.

URL: https://dev.mysql.com/doc/refman/8.0/en/string-type-syntax.html

