背景

生产环境插入数据报错：

java.sql.SQLException: Incorrect string value: '\xF0\xAC\xB1\x96' for column 'answer' at row 1

设置answer字段值为 “𬱖”出现错误
生僻字设置出错；

排查

编码

查看库表属性：

ENGINE InnoDB AUTO_INCREMENT =1479001 DEFAULT CHARSET utf8 ROW_FORMAT DYNAMIO

utf8

10.1.10.6 The utf8mb4 Character Set (4-Byte UTF-8 Unicode Encoding)
The character set named utf8 uses a maximum of three bytes per character and contains only BMP characters. As of MySQL 5.5.3, the utf8mb4 character set uses a maximum of four bytes per character supports supplemental characters:
For a BMP character, utf8 and utf8mb4 have identical storage characteristics: same code values, same encoding, same length.
For a supplementary character, utf8 cannot store the character at all, while utf8mb4 requires four bytes to store it. Since utf8 cannot store the character at all, you do not have any supplementary characters in utf8 columns and you need not worry about converting characters or losing data when upgrading utf8 data from older versions of MySQL.
utf8mb4 is a superset of utf8.

总而言之，utf-8 只支持 3 个字节的字符；
如果是超过 4 个字节，那么就需要使用 utf8mb4 （max byte 4 ）：加强版的 utf8 来存储

生僻字

查看生僻字占用的字节：

4 字节，显然 utf8 是不满足的

解决

提交 sql：

alter table qt_check_answer default  CHARACTER SET utf8mb4

alt 之后还是报错；
查看库表：

表级别的设置更新了，但是字段还没有更新；
复现一下：

结论

此时更新字段级别的编码类型：解决

结论：MySQL编码存在字段级别的设置，生僻字需要字段级别的编码支持