MyBatis简易教程（06）：MyBatisPlus的用法
MyBatis简易教程汇总，详见：https://www.cnblogs.com/uncleyong/p/17984096
简介
MyBatis-Plus（简称 MP），是一个MyBatis的增强工具包，只做增强不做改变，为简化开发、提高效率而生。
环境搭建
测试数据
SET FOREIGN_KEY_CHECKS=0; DROP TABLE IF EXISTS `user`; CREATE TABLE `user` ( `id` int(11) NOT NULL AUTO_INCREMENT, `username` varchar(20) NOT NULL COMMENT '用户名', `password` varchar(255) NOT NULL COMMENT '密码', `real_name` varchar(255) NOT NULL COMMENT '真实名', `sex` varchar(255) DEFAULT NULL COMMENT '性别', `birthday` date DEFAULT NULL COMMENT '生日', `phone` varchar(255) NOT NULL COMMENT '电话', `utype` tinyint(1) DEFAULT NULL COMMENT '用户类型', `addtime` datetime DEFAULT NULL COMMENT '添加时间', `adduser` varchar(255) DEFAULT NULL COMMENT '添加者', PRIMARY KEY (`id`), UNIQUE KEY `phone` (`phone`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; insert into `user` values(1,'qzcsbj1','62f7f5673e94eca261b8fce7ae7863a4','qzcsbj1','男','2018-09-06','13800000001',0,now(),'qzcsbj'); insert into `user` values(2,'qzcsbj2','62f7f5673e94eca261b8fce7ae7863a4','qzcsbj2','女','2018-09-07','13800000002',1,now(),'qzcsbj'); insert into `user` values(3,'qzcsbj3','62f7f5673e94eca261b8fce7ae7863a4','qzcsbj3','男','2018-09-08','13800000003',0,now(),'qzcsbj'); insert into `user` values(4,'qzcsbj4','62f7f5673e94eca261b8fce7ae7863a4','qzcsbj4','女','2018-09-09','13800000004',1,now(),'qzcsbj'); insert into `user` values(5,'qzcsbj5','62f7f5673e94eca261b8fce7ae7863a4','qzcsbj5','女','2018-09-10','13800000005',0,now(),'qzcsbj');
实体类
package com.qzcsbj.bean;
import java.util.Date;
/**
* @公众号 : 全栈测试笔记
* @博客 : www.cnblogs.com/uncleyong
* @微信 : ren168632201
* @描述 : <>
*/
public class User {
private Integer id; // 实体类推荐用包装类
private String username;
private String password;
private String realName;
private String sex;
private Date birthday;
private String phone;
private String utype;
private String addtime;
private String adduser;
public User() {
}
public User(String username, String password, String realName, String sex, Date birthday, String phone, String utype,String adduser, String addtime) {
this.username = username;
this.password = password;
this.realName = realName;
this.sex = sex;
this.birthday = birthday;
this.phone = phone;
this.utype = utype;
this.adduser = adduser;
this.addtime = addtime;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getRealName() {
return realName;
}
public void setRealName(String realName) {
this.realName = realName;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getUtype() {
return utype;
}
public void setUtype(String utype) {
this.utype = utype;
}
public String getAddtime() {
return addtime;
}
public void setAddtime(String addtime) {
this.addtime = addtime;
}
public String getAdduser() {
return adduser;
}
public void setAdduser(String adduser) {
this.adduser = adduser;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
", realName='" + realName + '\'' +
", sex='" + sex + '\'' +
", birthday=" + birthday +
", phone='" + phone + '\'' +
", utype='" + utype + '\'' +
", addtime=" + addtime +
", adduser='" + adduser + '\'' +
'}';
}
}
pom依赖
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.qzcsbj.mybatisplus</groupId>
<artifactId>mybatisplus</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<!-- mybatis-plus -->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus</artifactId>
<version>3.4.2</version>
</dependency>
<!-- mysql驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
<!-- https://mvnrepository.com/artifact/log4j/log4j -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
<!--单元测试-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
</resources>
</build>
</project>
说明：mybatis-plus包含了mybatis等相关依赖
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<properties resource="jdbc.properties"></properties>
<!--实体类取别名-->
<typeAliases>
<!--方法一：别名可以随意定义，比如：XXX，但是最好和类名一样，见名知意-->
<!--<typeAlias type="com.qzcsbj.bean.User22" alias="User2"/>-->
<!--方法二（推荐）：直接给所有的实体类取别名-->
<package name="com.qzcsbj.bean"/>
</typeAliases>
<!--配置MyBatis连接数据库-->
<!--环境-->
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
</environments>
<!--引入映射文件-->
<mappers>
<!--方法一：路径相对于资源目录根路径-->
<!--<mapper resource="com\qzcsbj\mapper\UserMapper.xml"/>-->
<!--<mapper resource="com/qzcsbj/mapper/UserMapper.xml"/>-->
<!--方法二：写接口全路径，此时映射文件名必须和接口名一样-->
<!--<mapper class="com.qzcsbj.mapper.UserMapper"/>-->
<!--方法三（推荐）：写接口的包名，直接映射包的名字-->
<package name="com.qzcsbj.mapper"/>
</mappers>
</configuration>
添加log4j.properties
### 根logger 设置### log4j.rootLogger=DEBUG, Console ### 输出信息到控制台 ### log4j.appender.Console=org.apache.log4j.ConsoleAppender log4j.appender.Console.layout=org.apache.log4j.PatternLayout log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n log4j.logger.java.sql.ResultSet=INFO log4j.logger.org.apache=INFO log4j.logger.java.sql.Connection=DEBUG log4j.logger.java.sql.Statement=DEBUG log4j.logger.java.sql.PreparedStatement=DEBUG
添加jdbc连接信息配置：jdbc.properties
jdbc.driver=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://192.168.117.180:3306/gift?useUnicode=true&characterEncoding=utf-8&useSSL=true jdbc.username=root jdbc.password=qzcsbj
工具类MyBatisUtils中集成mybatis-plus：使用MyBatisPlus的Session工厂
package com.qzcsbj.utils;
import com.baomidou.mybatisplus.core.MybatisSqlSessionFactoryBuilder;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
/**
* @公众号 : 全栈测试笔记
* @博客 : www.cnblogs.com/uncleyong
* @微信 : ren168632201
* @描述 : <>
*/
public class MyBatisUtils {
public static SqlSession getSession(){
SqlSession session=null;
InputStream inputStream=null;
try {
inputStream = Resources.getResourceAsStream("mybatis-config.xml");
// 使用MyBatisPlus的Session工厂
SqlSessionFactory sqlSessionFactory = new MybatisSqlSessionFactoryBuilder().build(inputStream);
session = sqlSessionFactory.openSession(true); // mybatis增、删、改要手动提交事务，true表示自动提交事务
return session;
} catch (IOException e) {
e.printStackTrace();
}finally {
if (inputStream != null){
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return null;
}
public static void closeSession(SqlSession session){
if(session != null){
session.close();
}
}
}
CRUD实现方式
1、基于mybatis编写UserMapper接口、CRUD方法，提供UserMapper.xml映射文件，并手动编写每个方法对应的SQL语句
2、基于mybatis-plus（MP）创建UserMapper接口，并继承BaseMapper接口，然后就可以使用MP完成相关操作，甚至不需要创建SQL映射文件（参考：https://baomidou.com/pages/10c804/#abstractwrapper），说明：只适用于单表
mapper接口
package com.qzcsbj.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.qzcsbj.bean.User;
import java.util.List;
/**
* @公众号 : 全栈测试笔记
* @博客 : www.cnblogs.com/uncleyong
* @微信 : ren168632201
* @描述 : <>
*/
public interface UserMapper extends BaseMapper<User> {
}
这个父接口里面有很多方法，mybatis-plus已经给我们写好了，直接调用即可
实体类注解
@TableName
@TableId
@TableField
package com.qzcsbj.bean;
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import java.util.Date;
/**
* @公众号 : 全栈测试笔记
* @博客 : www.cnblogs.com/uncleyong
* @微信 : ren168632201
* @描述 : <>
*/
@TableName(value = "user") // MybatisPlus默认会使用实体类类名去数据库找对应的表，如果实体类类名和表名一样，这个注解可以省略
public class User {
@TableId(value = "id", type = IdType.AUTO) // value是表中主键列的列名，如果和实体类属性名一样，可以省略不指定；type指定主键策略，IdType.AUTO表示这个字段在数据库表中是主键、且自增长
private Integer id; // 实体类推荐用包装类
// @TableField("username") // 如果不写，默认有一个@TableField("username")
private String username;
private String password;
// @TableField("real_name") // 可以省略不写，因为mybatisplus默认支持
private String realName;
private String sex;
private Date birthday;
private String phone;
private String utype;
private String addtime;
private String adduser;
@TableField(exist = false) // 忽略这个字段，和数据库没有映射关系，也就是表中没这个字段
private String job;
public User() {
}
public User(String username, String password, String realName, String sex, Date birthday, String phone, String utype,String adduser, String addtime) {
this.username = username;
this.password = password;
this.realName = realName;
this.sex = sex;
this.birthday = birthday;
this.phone = phone;
this.utype = utype;
this.adduser = adduser;
this.addtime = addtime;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getRealName() {
return realName;
}
public void setRealName(String realName) {
this.realName = realName;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getUtype() {
return utype;
}
public void setUtype(String utype) {
this.utype = utype;
}
public String getAddtime() {
return addtime;
}
public void setAddtime(String addtime) {
this.addtime = addtime;
}
public String getAdduser() {
return adduser;
}
public void setAdduser(String adduser) {
this.adduser = adduser;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
", realName='" + realName + '\'' +
", sex='" + sex + '\'' +
", birthday=" + birthday +
", phone='" + phone + '\'' +
", utype='" + utype + '\'' +
", addtime=" + addtime +
", adduser='" + adduser + '\'' +
'}';
}
}
示例：基础CRUD之增
测试类
package com.qzcsbj;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.qzcsbj.bean.User;
import com.qzcsbj.mapper.UserMapper;
import com.qzcsbj.utils.MyBatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import java.text.SimpleDateFormat;
import java.util.*;
/**
* @公众号 : 全栈测试笔记
* @博客 : www.cnblogs.com/uncleyong
* @微信 : ren168632201
* @描述 : <>
*/
public class testMybatis {
SqlSession session = null;
UserMapper userMapper = null;
@Before
public void init(){
System.out.println("初始化。。。");
session = MyBatisUtils.getSession();
userMapper = session.getMapper(UserMapper.class);
}
@After
public void destory(){
System.out.println("关闭session");
MyBatisUtils.closeSession(session);
}
// 新增用户
@Test
public void testAddUser(){
User user = new User("qzcsbj9","123456","qzcsbj9","男",new Date(),"13800000009","1","qzcsbj",new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));
int n = userMapper.insert(user);
System.out.println(n>0?"新增成功":"新增失败");
}
}
结果
示例：基础CRUD之删
// 根据id删除
@Test
public void testDeleteById(){
int n = userMapper.deleteById(9);
System.out.println(n>0?"删除成功":"删除失败");
}
// 根据map删除（单条件）
@Test
public void testDeleteByMap(){
Map<String,Object> map = new HashMap<String, Object>();
map.put("real_name","qzcsbj5"); // 根据真实名删除数据；这里写的是数据库里面的列名
int n = userMapper.deleteByMap(map);
System.out.println(n>0?"删除成功":"删除失败");
}
// 根据map删除（多条件，sql的条件是and关系，说明：这里条件只能是等值关系，不能是大于小于之类的）
@Test
public void testDeleteByMap2(){
Map<String,Object> map = new HashMap<String, Object>();
map.put("sex","男");
map.put("utype","1");
int n = userMapper.deleteByMap(map);
System.out.println(n>0?"删除成功":"删除失败");
}
// 批量删除，sql的条件是in
@Test
public void testDeleteBatch(){
List<Integer> ids = new ArrayList<Integer>();
ids.add(3);
ids.add(4);
int n = userMapper.deleteBatchIds(ids);
System.out.println(n>0?"删除成功":"删除失败");
}
示例：基础CRUD之改
// 根据id更新
@Test
public void testUpdateById(){
User user = userMapper.selectById(1);
user.setUsername("qzcsbj1-1");
user.setRealName("qzcsbj1-1");
int n = userMapper.updateById(user);
System.out.println(n>0?"更新成功":"更新失败");
}
示例：基础CRUD之查
// 根据id查找
@Test
public void testSelectById(){
User user = userMapper.selectById(1);
System.out.println(user);
}
// 根据map查找（多个条件是and关系）
@Test
public void testSelectByMap(){
Map<String,Object> map = new HashMap<String, Object>();
map.put("sex","男");
map.put("utype","0");
List<User> users = userMapper.selectByMap(map);
for (User user : users) {
System.out.println(user);
}
}
// 批量查找
@Test
public void testSelectBatch(){
List<Integer> ids = new ArrayList<Integer>();
ids.add(1);
ids.add(2);
List<User> users = userMapper.selectBatchIds(ids);
for (User user : users) {
System.out.println(user);
}
}
条件构造器
参考：https://baomidou.com/pages/10c804/#abstractwrapper
Wrapper类型的泛型参数，就是需要传一个条件构造器
示例：需要条件构造器之增
无方法
示例：需要条件构造器之删
@Test
public void testDelete(){
int n = userMapper.delete(new QueryWrapper<User>().eq("id", 1));
System.out.println(n>0?"删除成功":"删除失败");
}
示例：需要条件构造器之改
@Test
public void testUpdate(){
User user = new User("qzcsbj10","123456","qzcsbj10","男",new Date(),"13800000010","1","qzcsbj",new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));
int n = userMapper.update(user, new UpdateWrapper<User>().eq("id", 1));
System.out.println(n>0?"更新成功":"更新失败");
}
@Test
public void testUpdate2(){
User user = new User();
user.setSex("男");
int n = userMapper.update(user, new UpdateWrapper<User>().eq("id", 2));
System.out.println(n>0?"更新成功":"更新失败");
}
示例：需要条件构造器之查
无条件
// 如果传null，就是查找所有，select * from user
@Test
public void testSelectAll(){
List<User> users = userMapper.selectList(null);
for (User user : users) {
System.out.println(user);
}
}
多条件：and
// select * from user where id>=2 and sex = '女';
@Test
public void testQuery(){
QueryWrapper<User> qw = new QueryWrapper<User>();
// 多个条件，默认是and关系
qw.ge("id",2);
qw.eq("sex","女");
List<User> users = userMapper.selectList(qw);
for (User user : users) {
System.out.println(user);
}
}
多条件：or
// select * from user where id>=2 or sex = '男';
@Test
public void testQuery2(){
QueryWrapper<User> qw = new QueryWrapper<User>();
qw.ge("id",2);
qw.or(); // 设置多个条件是or的关系
qw.eq("sex","男");
List<User> users = userMapper.selectList(qw);
for (User user : users) {
System.out.println(user);
}
}
多条件：or和and混用
// select * from user where id>=2 or (sex = '男' and id<=8);
@Test
public void testQuery3(){
QueryWrapper<User> qw = new QueryWrapper<User>();
qw.ge("id",2);
qw.or(i -> i.eq("sex","男").le("id",8)); // lambdas表达式
List<User> users = userMapper.selectList(qw);
for (User user : users) {
System.out.println(user);
}
}
between and
// 查一个范围，select * from user where id between 1 and 2 and utype='0';
@Test
public void testQuery4(){
List<User> users = userMapper.selectList(new QueryWrapper<User>().between("id", 1, 2).eq("utype","0"));
for (User user : users) {
System.out.println(user);
}
}
// 查一个范围，select * from user where id between 1 and 2 or utype='0';
@Test
public void testQuery5(){
List<User> users = userMapper.selectList(new QueryWrapper<User>().between("id", 1, 2).or().eq("utype","0"));
for (User user : users) {
System.out.println(user);
}
}
in
@Test
public void testIn(){
List<Integer> ids = new ArrayList<>();
ids.add(1);
ids.add(2);
List<User> users = userMapper.selectList(new QueryWrapper<User>().in("id", ids));
for (User user : users) {
System.out.println(user);
}
}
模糊查询
// 模糊查询，select * from user where username like "%qzcs%";
@Test
public void testLike(){
List<User> users = userMapper.selectList(new QueryWrapper<User>().like("username", "qzcs"));
for (User user : users) {
System.out.println(user);
}
}
// 模糊查询，select * from user where username not like "%qzcs%";
@Test
public void testNotLike(){
List<User> users = userMapper.selectList(new QueryWrapper<User>().notLike("username", "qzcs"));
for (User user : users) {
System.out.println(user);
}
}
// 模糊查询，select * from user where username like "qzcs%";
@Test
public void testRightLike(){
List<User> users = userMapper.selectList(new QueryWrapper<User>().likeRight("username", "qzcs"));
for (User user : users) {
System.out.println(user);
}
}
// 模糊查询，select * from user where username like "%bj2";
@Test
public void testLeftLike(){
List<User> users = userMapper.selectList(new QueryWrapper<User>().likeLeft("username", "bj2"));
for (User user : users) {
System.out.println(user);
}
}
null、not null
// 非空，select * from user where sex is not null;
@Test
public void testNotNull(){
List<User> users = userMapper.selectList(new QueryWrapper<User>().isNotNull("sex"));
for (User user : users) {
System.out.println(user);
}
}
查总数
// 查总数，select count(*) from user where sex is not null;
@Test
public void testCount(){
Integer n = userMapper.selectCount(new QueryWrapper<User>().isNotNull("sex"));
System.out.println("总数为：" + n);
}
排序
// 排序，一个排序字段，select * from user where id between 1 and 2 or utype='0' order by id asc;
@Test
public void testQuery6(){
List<User> users = userMapper.selectList(new QueryWrapper<User>().between("id", 1, 2).or().eq("utype","0").orderByAsc("id"));
for (User user : users) {
System.out.println(user);
}
}
// 排序，多个排序字段，select * from user where id between 1 and 2 or utype='0' order by id asc, username desc;
@Test
public void testQuery7(){
List<User> users = userMapper.selectList(new QueryWrapper<User>().between("id", 1, 2).or().eq("utype","0").orderByAsc("id").orderByDesc("username"));
for (User user : users) {
System.out.println(user);
}
}
聚合查询
// 聚合查询：select max(id),min(id) from user
@Test
public void testQuery8(){
List<Map<String, Object>> lists = userMapper.selectMaps(new QueryWrapper<User>().select("min(id)", "max(id)"));
for (Map<String, Object> list : lists) {
System.out.println(list);
}
}
@Test
public void testQuery8_2(){
// List<Map<String, Object>> lists = userMapper.selectMaps(new QueryWrapper<User>().select("min(id)", "max(id)"));
List<Map<String, Object>> lists = userMapper.selectMaps(new QueryWrapper<User>().select("min(id),max(id)"));
System.out.println(lists.size());
Map<String, Object> map = lists.get(0);
Set<Map.Entry<String, Object>> entries = map.entrySet();
for (Map.Entry<String, Object> entry : entries) {
System.out.println(entry.getKey() + "--->" + entry.getValue());
}
}
聚合、分组查询
// 分组查询：select max(id),min(id),sex from user group by sex
@Test
public void testQuery9(){
// List<Map<String, Object>> lists = userMapper.selectMaps(new QueryWrapper<User>().select("min(id)", "max(id)","sex").groupBy("sex"));
List<Map<String, Object>> lists = userMapper.selectMaps(new QueryWrapper<User>().select("min(id), max(id),sex").groupBy("sex").orderByAsc("min(id)"));
for (Map<String, Object> list : lists) {
System.out.println(list);
}
}
// 分组查询：select max(id),min(id),sex from user group by sex
@Test
public void testQuery9_2(){
// List<Map<String, Object>> lists = userMapper.selectMaps(new QueryWrapper<User>().select("min(id)", "max(id)","sex").groupBy("sex"));
List<Map<String, Object>> lists = userMapper.selectMaps(new QueryWrapper<User>().select("min(id), max(id),sex").groupBy("sex").orderByAsc("min(id)"));
System.out.println(lists.size());
for (Map<String, Object> map : lists) {
Set<Map.Entry<String, Object>> entries = map.entrySet();
for (Map.Entry<String, Object> entry : entries) {
System.out.println(entry.getKey() + "--->" + entry.getValue());
}
}
}
分组条件having
// 分组查询：select max(id),min(id),sex from user group by sex having min(id)>1 order by min(id) asc
@Test
public void testQuery10(){
// List<Map<String, Object>> lists = userMapper.selectMaps(new QueryWrapper<User>().select("min(id)", "max(id)","sex").groupBy("sex"));
List<Map<String, Object>> lists = userMapper.selectMaps(new QueryWrapper<User>().select("min(id), max(id),sex").groupBy("sex").having("min(id)>1").orderByAsc("min(id)"));
for (Map<String, Object> list : lists) {
System.out.println(list);
}
}
// 分组查询：select max(id),min(id),sex from user group by sex having min(id)>1 order by min(id) asc
@Test
public void testQuery10_2(){
// List<Map<String, Object>> lists = userMapper.selectMaps(new QueryWrapper<User>().select("min(id)", "max(id)","sex").groupBy("sex"));
List<Map<String, Object>> lists = userMapper.selectMaps(new QueryWrapper<User>().select("min(id), max(id),sex").groupBy("sex").having("min(id)>1").orderByAsc("min(id)"));
for (Map<String, Object> map : lists) {
Set<Map.Entry<String, Object>> entries = map.entrySet();
for (Map.Entry<String, Object> entry : entries) {
System.out.println(entry.getKey() + "--->" + entry.getValue());
}
}
}
说明：如果构造器没法满足，就要自己写sql（写mapper接口、映射文件）
原文会持续更新，原文地址：https://www.cnblogs.com/uncleyong/p/17017064.html
__EOF__
本文作者：持之以恒（韧）
关于博主：擅长性能、全链路、自动化、企业级自动化持续集成（DevTestOps）、测开等
面试必备：项目实战（性能、自动化）、简历笔试，https://www.cnblogs.com/uncleyong/p/15777706.html
测试提升：从测试小白到高级测试修炼之路，https://www.cnblogs.com/uncleyong/p/10530261.html
欢迎分享：如果您觉得文章对您有帮助，欢迎转载、分享，也可以点击文章右下角【推荐】一下！
关于博主：擅长性能、全链路、自动化、企业级自动化持续集成（DevTestOps）、测开等
面试必备：项目实战（性能、自动化）、简历笔试，https://www.cnblogs.com/uncleyong/p/15777706.html
测试提升：从测试小白到高级测试修炼之路，https://www.cnblogs.com/uncleyong/p/10530261.html
欢迎分享：如果您觉得文章对您有帮助，欢迎转载、分享，也可以点击文章右下角【推荐】一下！
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