Mybatis笔记整理2（各种关联查询）

POJO类，均省略setget与tostring方法

User类

public class User implements Serializable {private static final long serialVersionUID = 1L;private Integer id;private String username;// 用户姓名private String sex;// 性别private Date birthday;// 生日private String address;// 地址//附加对象Listprivate List<Orders> ordersList;}

Order类

public class Orders  implements Serializable{private static final long serialVersionUID = 1L;private Integer id;private Integer userId;private String number;private Date createtime;private String note;    //附加对象  用户对象private User user;

QueryVo

public class QueryVo implements Serializable {private static final long serialVersionUID = 1L;private User user;Integer[] ids;}

UserMapper各种查询

UserMapper

public interface UserMapper {//遵循四个原则//接口 方法名  == User.xml 中 id 名//返回值类型  与  Mapper.xml文件中返回值类型要一致//方法的入参类型 与Mapper.xml中入参的类型要一致//命名空间 绑定此接口public User findUserById(Integer id);public List<User> findUserByQueryVo(QueryVo vo);//查询数据条数public Integer countUser();//根据性别和名字查询用户public  List<User> selectUserBySexAndUsername(User user);//根据多个id查询用户信息//public List<User>  selectUserByIds(QueryVo  vo);public List<User>  selectUserByIds(@Param(value="idarray")Integer[] ids);//public List<User>  selectUserByIds(List<Integer> ids);}

UserMapper.xml

<?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">
<!-- 写Sql语句   -->
<mapper namespace="com.itheima.mybatis.mapper.UserMapper"><sql id="selector">select * from user</sql><!-- 通过ID查询一个用户 --><select id="findUserById" parameterType="Integer" resultType="User">select * from user where id = #{v}</select><!-- //根据用户名称模糊查询用户列表#{}    select * from user where id = ？    占位符  ? ==  '五'${}    select * from user where username like '%五%'  字符串拼接  --><select id="findUserByUsername" parameterType="String" resultType="com.itheima.mybatis.pojo.User">select * from user where username like "%"#{haha}"%"</select><!-- 添加用户 --><insert id="insertUser" parameterType="com.itheima.mybatis.pojo.User"><selectKey keyProperty="id" resultType="Integer" order="AFTER">select LAST_INSERT_ID()</selectKey>insert into user (username,birthday,address,sex) values (#{username},#{birthday},#{address},#{sex})</insert><!-- 更新 --><update id="updateUserById" parameterType="com.itheima.mybatis.pojo.User">update user set username = #{username},sex = #{sex},birthday = #{birthday},address = #{address}where id = #{id}</update><!-- 删除 --><delete id="deleteUserById" parameterType="Integer">delete from user where id = #{vvvvv}</delete><!-- 根据用户名模糊查询 --><select id="findUserByQueryVo" parameterType="QueryVo" resultType="com.itheima.mybatis.pojo.User">select * from user where username like "%"#{user.username}"%"</select><!-- 查询用户条数--><select id="countUser"  resultType="Integer">select count(*) from user </select><!-- 根据性别和名字查询用户     where可以去掉第一个and   前  后 --><select id="selectUserBySexAndUsername" parameterType="User" resultType="User"><include refid="selector"></include><where><if test="sex !=null and sex !=''">and sex=#{sex}   </if><if test="username !=null and username!=''">and username=#{username}</if></where></select><!-- 多个ID --><select id="selectUserByIds"  parameterType="QueryVo"  resultType="User"><include refid="selector"></include><where>id in<foreach collection="idarray"  item="id"  separator="," open="("  close=")">#{id} </foreach></where></select>
</mapper>

数据库操作

public class MybatisMapperTest {//根据ID查询@Testpublic void testMapper() throws Exception {//加载核心配置文件String resource = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(resource);//创建SqlSessionFactorySqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//创建SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//SqlSEssion帮我生成一个实现类  （给接口）UserMapper userMapper = sqlSession.getMapper(UserMapper.class);User user = userMapper.findUserById(10);System.out.println(user);}//根据包装类模糊查询@Testpublic void testMapperQueryVo() throws Exception {//加载核心配置文件String resource = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(resource);//创建SqlSessionFactorySqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//创建SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//SqlSEssion帮我生成一个实现类  （给接口）UserMapper userMapper = sqlSession.getMapper(UserMapper.class);QueryVo  vo =new QueryVo();User  user =new User();user.setUsername("五");vo.setUser(user);List<User> us = userMapper.findUserByQueryVo(vo);for (User u : us) {System.out.println(u);}}//简单类型查询@Testpublic void testMapperQueryVoCount() throws Exception {//加载核心配置文件String resource = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(resource);//创建SqlSessionFactorySqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//创建SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//SqlSEssion帮我生成一个实现类  （给接口）UserMapper userMapper = sqlSession.getMapper(UserMapper.class);QueryVo  vo =new QueryVo();User  user =new User();user.setUsername("五");vo.setUser(user);Integer i = userMapper.countUser();System.out.println(i);}//查询订单表order的所有数据@Testpublic void testOrderList() throws Exception {//加载核心配置文件String resource = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(resource);//创建SqlSessionFactorySqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//创建SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//SqlSEssion帮我生成一个实现类  （给接口）OrderMapper mapper = sqlSession.getMapper(OrderMapper.class);List<Orders> ordersList = mapper.selectOrdersList();for (Orders orders : ordersList) {System.out.println(orders);}}//  根据性别和名字查询用户 @Testpublic void testfindUserBySexAndUsername() throws Exception {//加载核心配置文件String resource = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(resource);//创建SqlSessionFactorySqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//创建SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//SqlSEssion帮我生成一个实现类  （给接口）UserMapper mapper = sqlSession.getMapper(UserMapper.class);User user=new User();//user.setSex("女");user.setUsername("天海翼");List<User> users = mapper.selectUserBySexAndUsername(user);for (User user2 : users) {System.out.println(user2);}}//  根据多个ID查询用户 @Testpublic void testfindUserIDs() throws Exception {//加载核心配置文件String resource = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(resource);//创建SqlSessionFactorySqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//创建SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//SqlSEssion帮我生成一个实现类  （给接口）UserMapper mapper = sqlSession.getMapper(UserMapper.class);/*列表* QueryVo  vo=new QueryVo();List<Integer>  id=new ArrayList<>();id.add(24);id.add(25);id.add(28);vo.setIdsList(id);  List<User> ids = mapper.selectUserByIds(vo);for (User user : ids) {System.out.println(user);}*///QueryVo  vo=new QueryVo();/*Integer [] ids = new Integer[2];ids[0]=1;ids[1]=26;*/Integer[] ids = {1,28};//vo.setIds(ids);List<User> users = mapper.selectUserByIds(ids);for (User user : users) {System.out.println(user);}}
}

用户订单关联查询

OrderMapper

public interface OrderMapper {// 查询订单表order的所有数据public List<Orders>  selectOrdersList();//一对一关联查询，以订单为中心，关联用户public List<Orders> selectOrders();//一对多关联,以用户为中心public List<User>  selectUserList();}

OrderMapper.xml

<?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">
<!-- 写Sql语句   -->
<mapper namespace="com.itheima.mybatis.mapper.OrderMapper"><!-- 查询订单表order的所有数据 --><!-- <select id="selectOrdersList" resultType="Orders"> --><resultMap type="Orders" id="orders"><id column="id" property="id"/><result column="user_id" property="userId"/><result column="createtime" property="createtime"/><result column="note" property="note"/></resultMap><select id="selectOrdersList"  resultMap="orders">select id,user_id,number,createtime, note from orders</select><!-- 一对一关联查询，以订单为中心，关联用户 --><!-- 定义Javabean（Orders）与数据库表orders之间映射 --><resultMap type="Orders" id="order">     <id column="id"  property="id"/><result column="createtime"  property="createtime"/> <result column="user_id"  property="userId"/><result column="number"  property="number"/><result column="note"  property="note"/><!-- 一对一 --><!-- 定义User自身属性和与数据库表user之间字段映射 --><association property="user"  javaType="User"><id column="id" property="id"/><result  column="username" property="username"/><result  column="sex" property="sex"/><result  column="birthday" property="birthday"/><result  column="address" property="address"/></association></resultMap><select id="selectOrders"  resultMap="order">SELECT  o.id,o.user_id,o.number,o.note,o.createtime,u.username  FROM orders o  LEFT JOIN USER u  ON o.user_id=u.id</select><!-- 一对多关联,以用户为中心 --><resultMap type="User" id="user"><id  column="id"  property="id"/><result column="username"  property="username"/><result column="sex"  property="sex"/><result column="birthday"  property="birthday"/><result column="address"  property="address"/><!-- 一对多 --><collection property="ordersList"  ofType="Orders"><id  column="id"  property="id"/><result  column="user_id"  property="userId"/><result column="number"  property="number"/> <result column="createtime"  property="createtime"/> <result column="note"  property="note"/> </collection></resultMap><select id="selectUserList"  resultMap="user">SELECT  o.id,o.user_id,o.number,o.createtime,u.username  FROM  USER u  LEFT JOIN  orders oON o.user_id=u.id  </select></mapper>

关联查询

public class MybatisMapperTest2 {//一对一关联查询，以订单为中心，关联用户@Testpublic void testOrderList() throws Exception {//加载核心配置文件String resource = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(resource);//创建SqlSessionFactorySqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//创建SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//SqlSEssion帮我生成一个实现类  （给接口）OrderMapper orderMapper = sqlSession.getMapper(OrderMapper.class);List<Orders> selectOrdersList = orderMapper.selectOrders();for (Orders orders : selectOrdersList) {System.out.println(orders);}}//一对多关联查询，以用户为中心，关联用户@Testpublic void testUserList() throws Exception {//加载核心配置文件String resource = "sqlMapConfig.xml";InputStream in = Resources.getResourceAsStream(resource);//创建SqlSessionFactorySqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);//创建SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession();//SqlSEssion帮我生成一个实现类  （给接口）OrderMapper orderMapper = sqlSession.getMapper(OrderMapper.class);List<User> users = orderMapper.selectUserList();for (User user : users) {System.out.println(user);}}}

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Mybatis笔记整理2（各种关联查询）

UserMapper各种查询

用户订单关联查询

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