is not online, it can be changed with a little effort.
change the project code, file storage code, filter code, and the encoding declaration on the page if there is a jsp.

if there is a place to determine the length of the field, the UTF8 is three bytes, and the GBK is 2 bytes, which also needs to be modified.

of course, the best way is to convince the customer that if the database is empty and the customer does not want to bother to modify it, you can do it yourself if you give it permission, but it is unlikely to change it if you put it with other databases.