emoji错误：ER_TRUNCATED_WRONG_VALUE_FOR_FIELD: Incorrect string value:

原因在于mysql数据库编码格式utf8默认保存的是1到3个字节，而emoji表情采用4个字节保存，所以抛出异常。因此需要将编码格式转换为utf8mb4（mysql版本大于5.5）

设置数据库编码

// 设置编码
SET NAMES utf8mb4; 
ALTER DATABASE `database_name` CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci;

查看数据库当前编码状态

// 查看编码状态
SHOW VARIABLES WHERE Variable_name LIKE 'character_set_%' OR Variable_name LIKE 'collation%';

// 查看编码是否如下所示
character_set_client  utf8mb4
character_set_connection  utf8mb4
character_set_database    utf8mb4
character_set_filesystem  binary
character_set_results utf8mb4
character_set_server  utf8mb4
character_set_system  utf8
character_sets_dir    /usr/local/mysql/share/charsets/
collation_connection  utf8mb4_general_ci
collation_database    utf8mb4_general_ci
collation_server  utf8mb4_unicode_ci

设置mysql连接chatset编码

// 最容易被忽略的步骤：mysql连接组件
var connection = mysql.createConnection({
    host : 'host',
    user : 'user',
    password : 'password',
    database : 'database',
    charset : 'utf8mb4'
});

原文地址：http://www.fidding.me/article/43

happy coding!