一、简单的增删查改

1.添加

<insert id="insertUser">insert into user values (null,"cc","123445",20);
</insert>

2.删除

<!--    int deleteUser();--><delete id="deleteUser">delete  from user where id=3;</delete>

3.修改

<!--    void updateUser();--><update id="updateUser">update user set username='aa' where id=4;</update>

4.查询

查询功能的标签必须设置resultType或resultMap

• resultType:设置默认的映射关系
• resultmap:设置自定义的映射关系

<!--    User getUserById();--><select id="getUserById" resultType="com.mybatis.Bean.User">select * from user where id = 3;</select>