在插入语句中，您不会有一个现有的行来执行 where 子句吗?您正在插入一个新行，您的意思是要执行更新语句吗?

In an insert statement you wouldn't have an existing row to do a where claues on? You are inserting a new row, did you mean to do an update statment?

update users set username='JACK' and password='123' WHERE id='1';