(MyBatis-plus is simply a Mybatis enhancement tool to simplify development and improve efficiency. The abbreviation mp is used below to simplify MyBatis-plus, which is dedicated to enhancing MyBatis without changing it, and is born to simplify development and improve efficiency. Although Mybatis provides us with great convenience, it still has shortcomings. In fact, nothing is perfect. The existence of MP is to make up for the shortcomings of Mybatis.)