When inputting an expression in the input box, an error is reported: incorrect string value:'\xf0\x9f... ' for column 'XXX' at row 1

One 、 The reason for the error ：

This problem , as a result of UTF-8 The code may be 2-4 Bytes .Emoji Expressions or some special characters are 4 Bytes , and Mysql Of utf8 Code the most 3 Bytes , So the data doesn't plug in .

Two 、 Solution ：

1. stay mysql Found in the installation directory of my.ini, Make the following changes ：

[mysqld]
#  Set character set 
loose-default-character-set = utf8mb4

[client] 
# Set client character set 
default-character-set = utf8mb4

Configuration instructions ：
[client] Represents the default settings of the client ;
[mysql] Use... On behalf of us mysql Command login mysql Default settings for database ;
[mysqld] Represents the default settings of the database itself ;

2. stay my.ini Add the following settings in ：

character-set-client-handshake = FALSE
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci
init_connect='SET NAMES utf8mb4'

[mysql]
default-character-set = utf8mb4

Be careful ： front 4 The paragraph should be placed in [mysqld] Inside the back position .

3. Modify... In the database mysql The field attribute corresponding to the database is utf8mb4：

ALTER TABLE `a`
MODIFY COLUMN `content`  varchar(4000) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT ' Content ' AFTER `user_id`;

explain ：a： Table name ,content： Enter the field of expression .
If not , Then set the coding format of the database , as follows ：

ALTER DATABASE aaa CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci;

explain ：aaa： Database name

4. modify java in jdbc.properties Configuration of

jdbc.url=jdbc:mysql://localhost:3306/aaa?useServerPrepStmts=true&rewriteBatchedStatements=true&useUnicode=true&autoReconnect=true

Be careful ： Don't have “&characterEncoding=UTF-8”

5. restart mysql service

Return page , Input the expression randomly to test .