MySQL 插入前触发 - 截断不正确的 DOUBLE 错误

MySQL trigger before insert - truncated incorrect DOUBLE error

我想将新用户名与字符串连接起来,我有以下触发器:

CREATE DEFINER=`root`@`localhost` TRIGGER `rating_platform`.`admins_BEFORE_INSERT` BEFORE INSERT ON `admins` FOR EACH ROW
BEGIN
SET NEW.username = NEW.username + "test";
END

我收到此错误:

ERROR 1292: 1292: Truncated incorrect DOUBLE value: 'test'

我做错了什么?

使用CONCAT函数:

SET NEW.username = CONCAT(NEW.username,"test");