CREATE DATABASE db_name DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
CREATE DATABASE 的語法：
CREATE {DATABASE | SCHEMA} [IF NOT EXISTS] db_name
[create_specification [, create_specification] ...]
create_specification:
[DEFAULT] CHARACTER SET charset_name
| [DEFAULT] COLLATE collation_name
更改數據庫的字符編碼
ALTER DATABASE db_name DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci