package com.ys.mapper;

 

import org.apache.ibatis.annotations.Delete;

import org.apache.ibatis.annotations.Insert;

import org.apache.ibatis.annotations.Select;

import org.apache.ibatis.annotations.Update;

 

import com.ys.po.User;

 

public interface UserMapper {

  //根據(jù) id 查詢 user 表數(shù)據(jù)

  public User selectUserById(int id) throws Exception;

 

  //向 user 表插入一條數(shù)據(jù)

  public void insertUser(User user) throws Exception;

   

  //根據(jù) id 修改 user 表數(shù)據(jù)

  public void updateUserById(User user) throws Exception;

   

  //根據(jù) id 刪除 user 表數(shù)據(jù)

  public void deleteUserById(int id) throws Exception;

} 

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE mapper

 PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

 "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.ys.mapper.UserMapper">

 

   

  <!-- 根據(jù) id 查詢 user 表中的數(shù)據(jù)

    id:唯一標(biāo)識符，此文件中的id值不能重復(fù)

    resultType:返回值類型，一條數(shù)據(jù)庫記錄也就對應(yīng)實體類的一個對象

    parameterType:參數(shù)類型，也就是查詢條件的類型

  -->

  <select id="selectUserById"

      resultType="com.ys.po.User" parameterType="int">

    <!-- 這里和普通的sql 查詢語句差不多，后面的 #{id}表示占位符，里面不一定要寫id,寫啥都可以，但是不要空著 -->

    select * from user where id = #{id1}

  </select>

   

   

   

  <!-- 根據(jù) id 更新 user 表的數(shù)據(jù) -->

  <update id="updateUserById" parameterType="com.ys.po.User">

    update user u

      <!-- <set>

        <if test="username != null and username != ''">

          u.username = #{username},

        </if>

        <if test="sex != null and sex != ''">

          u.sex = #{sex}

        </if>

      </set> -->

      <trim prefix="set" suffixOverrides=",">

        <if test="username != null and username != ''">

          u.username = #{username},

        </if>

        <if test="sex != null and sex != ''">

          u.sex = #{sex},

        </if>

      </trim>

     

     where id=#{id}

  </update>

   

   

  <!-- 向 user 表插入一條數(shù)據(jù) -->

  <insert id="insertUser" parameterType="com.ys.po.User">

    <!-- 將插入的數(shù)據(jù)主鍵返回到 user 對象中

       keyProperty:將查詢到的主鍵設(shè)置到parameterType 指定到對象的那個屬性

       select LAST_INSERT_ID()：查詢上一次執(zhí)行insert 操作返回的主鍵id值，只適用于自增主鍵

       resultType:指定 select LAST_INSERT_ID() 的結(jié)果類型

       order:AFTER，相對于 select LAST_INSERT_ID()操作的順序

     -->

    <selectKey keyProperty="id" resultType="int" order="AFTER">

      select LAST_INSERT_ID() 

    </selectKey>

    insert into user(username,sex,birthday,address)

      value(#{username},#{sex},#{birthday},#{address})

  </insert>

   

   

   

  <!-- 根據(jù) id 刪除 user 表的數(shù)據(jù) -->

  <delete id="deleteUserById" parameterType="int">

    delete from user where id=#{id}

  </delete>

   

</mapper> 

//根據(jù)id查詢user表數(shù)據(jù)

@Test

public void testSelectUserById(){

  /*這個字符串由 userMapper.xml 文件中 兩個部分構(gòu)成

    <mapper namespace="com.ys.po.userMapper"> 的 namespace 的值

    <select id="selectUserById" > id 值*/

  String statement = "com.ys.mapper.UserMapper.selectUserById";

  User user = session.selectOne(statement, 1);

  System.out.println(user);

  session.close();

} 

<mappers>

    <!--批量加載mapper

     指定 mapper 接口的包名，mybatis自動掃描包下的mapper接口進(jìn)行加載

     -->

    <package name="com.ys.mapper"/>

</mappers>