mybatis增删改查

<mapper namespace="com.mybatis.test.IUserOperation">    <!-- select语句 -->    <select id="selectUserByID" parameterType="int" resultType="User">        select * from `user` where user.id = #{id}    </select>        <!-- 定义的resultMap，可以解决类的属性名和数据库列名不一致的问题-->    <!-- <resultMap type="User" id="userResultMap">        <id property="id" column="user_id"  />        <result property="userName" column="user_userName"  />        <result property="userAge" column="user_userAge"  />        <result property="userAddress" column="user_userAddress"  />    </resultMap> -->        <!-- 返回list的select语句，注意 resultMap的值是指向前面定义好的 -->    <!-- <select id="selectUsersByName" parameterType="string" resultMap="userResultMap">        select * from user where user.userName = #{userName}    </select> -->        <select id="selectUsersByName" parameterType="string" resultType="User">        select * from user where user.userName = #{userName}    </select>        <!--执行增加操作的SQL语句。id和parameterType分别与IUserOperation接口中的addUser方法的名字和参数类型一致。    useGeneratedKeys设置为"true"表明要MyBatis获取由数据库自动生成的主键；keyProperty="id"指定把获取到的主键值注入到User的id属性-->     <insert id="addUser" parameterType="User"         useGeneratedKeys="true" keyProperty="id">         insert into user(userName,userAge,userAddress)               values(#{userName},#{userAge},#{userAddress})      </insert>        <update id="updateUser" parameterType="User" >        update user set userName=#{userName},userAge=#{userAge},userAddress=#{userAddress} where id=#{id}    </update>        <delete id="deleteUser" parameterType="int">        delete from user where id=#{id}    </delete>    </mapper>