执行以下命令：
SET names utf8mb4;
完事，问题解决！
验证修改结果：
SHOW VARIABLES WHERE Variable_name LIKE 'character\_set\_%' OR Variable_name LIKE 'collation%';
+--------------------------+--------------------+
| 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 | latin1 |
| character_set_system | utf8 |
| collation_connection | utf8mb4_general_ci |
| collation_database | utf8_general_ci |
| collation_server | latin1_swedish_ci |
+--------------------------+--------------------+
