Mybatis-Plus--分页/多表联合查询--方法/使用/教程/实例

忘是亡心i 2022-09-17 03:18 376阅读 0赞

原文网址：[Mybatis-Plus--分页/多表联合查询--方法/使用/教程/实例\_IT利刃出鞘的博客-CSDN博客][Mybatis-Plus--_--_IT_-CSDN]

# 简介 #

本文用实例介绍MybatisPlus的分页以及多表联合查询的方法。

# 公共代码 #

**分页插件新写法（3.4.0及之后）**

import com.baomidou.mybatisplus.annotation.DbType;
    import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
     
    @Configuration
    public class MybatisPlusConfig {
     
        // 分页插件
        @Bean
        public MybatisPlusInterceptor mybatisPlusInterceptor() {
            MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
            interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
            return interceptor;
        }
    }

**分页插件老写法（3.4.0之前）**

import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    @Configuration
    public class MybatisPlusConfig {
    
        // 分页插件
        @Bean
        public PaginationInterceptor paginationInterceptor() {
            PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
            // 设置请求的页面大于最大页后操作， true调回到首页，false 继续请求  默认false
            // paginationInterceptor.setOverflow(false);
            // 设置最大单页限制数量，默认 500 条，-1 不受限制
            // paginationInterceptor.setLimit(500);
            // 开启 count 的 join 优化,只针对部分 left join
            paginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));
            return paginationInterceptor;
        }
    }

**entity**

@Data
    @TableName("t_question")
    public class Question implements Serializable {
    
        private static final long serialVersionUID = 1L;
    
        // 问答主键id
        @TableId(value = "id", type = IdType.AUTO)
        private Integer id;
    
        // 学生外键id
        @TableField("student_id")
        private Integer studentId;
    
        // 问题内容
        private String content;
    
        // 问题悬赏的积分
        private Integer value;
    }

@Data
    @TableName("t_student")
    public class Student implements Serializable {
    
        private static final long serialVersionUID = 1L;
    
        // 学生主键id
        @TableId(value = "id", type = IdType.AUTO)
        private Integer id;
    
        // 学生名称
        private String name;
    
        // 学生积分数
        private Integer points;
    }

**VO**

@Data
    public class QuestionStudentVO implements Serializable {
        // 问题主键id
        private Integer id;
    
        // 问题内容
        private String content;
    
        // 问题悬赏的积分
        private Integer value;
    
        // 学生外键id
        private Integer studentId;
    
        // 学生名字
        private List<String> name;
    
        // 学生积分
        private Integer points;
    }

**启动类**

package com.example;
    
    import org.mybatis.spring.annotation.MapperScan;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    
    @SpringBootApplication
    @MapperScan("com.example.mapper")
    public class MpPlusApplication {
        public static void main(String[] args) {
            SpringApplication.run(MpPlusApplication.class, args);
        }
    }

**sql**

USE mp;
    DROP TABLE IF EXISTS `t_question`;
    CREATE TABLE `t_question` (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      `student_id` int(11) DEFAULT NULL,
      `content` varchar(64) DEFAULT NULL,
      `value` int(11) DEFAULT NULL,
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=1002 DEFAULT CHARSET=utf8;
     
     
    BEGIN;
    INSERT INTO `t_question` VALUES ('1001', '1', 'this is question content', '10');
    INSERT INTO `t_question` VALUES ('1002', '2', 'this is question content', '30');
    COMMIT;
    
    DROP TABLE IF EXISTS `t_student`;
    CREATE TABLE `t_student` (
      `id` int(11) NOT NULL,
      `name` varchar(64) DEFAULT NULL,
      `points` int(11) DEFAULT NULL,
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
     
    BEGIN;
    INSERT INTO `t_student` VALUES ('1', 'Iron Man', '201');
    INSERT INTO `t_student` VALUES ('2', 'Jarvis', '100');
    INSERT INTO `t_student` VALUES ('3', 'Tony', '300');
    COMMIT;

**分页插件**

package com.example.conf;
    
    import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
    import org.mybatis.spring.annotation.MapperScan;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.transaction.annotation.EnableTransactionManagement;
    
    @EnableTransactionManagement
    @Configuration
    public class MybatisPlusConfig {
    
        // 分页插件
        @Bean
        public PaginationInterceptor paginationInterceptor() {
            return new PaginationInterceptor();
        }
    }

# 多表查询 #

**其他网址**

[mybatis Plus 多表联合查询][mybatis Plus]

## 代码 ##

**mapper**

package com.example.mapper;
    
    import com.baomidou.mybatisplus.core.mapper.BaseMapper;
    import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
    import com.example.entity.Question;
    import com.example.vo.QuestionStudentVO;
    import org.apache.ibatis.annotations.Select;
    
    import java.util.List;
    
    public interface QuestionMapper extends BaseMapper<Question> {
        @Select("SELECT t_question.*,t_student.`name`,t_student.`points` " + 
                " FROM t_question,t_student " +
                " WHERE t_question.student_id=t_student.id")
        List<QuestionStudentVO> getQuestionStudent();
    
        @Select("SELECT t_student.name " + 
    	        " FROM t_question,t_student " +
                " WHERE t_question.student_id = #{id} " +
                "    AND t_question.student_id=t_student.id")
        List<String> getStudentNameByQuestionId(@Param("id") Long id);
    
        @Select("SELECT t_student.name " + 
    	        " FROM t_question,t_student " +
                " ${ew.customSqlSegment} " +
                "    AND t_question.student_id=t_student.id")
        List<String> getStudentNamesByQuestionIds(@Param("ew") Wrapper wrapper);
    }

**controller**

package com.example.controller;
    
    import com.baomidou.mybatisplus.core.metadata.IPage;
    import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
    import com.example.entity.Student;
    import com.example.service.QuestionService;
    import com.example.service.StudentService;
    import com.example.vo.QuestionStudentVO;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.Collections;
    import java.util.List;
    
    @RestController
    @RequestMapping("/common")
    public class CommonController {
        @Autowired
        QuestionService questionService;
    
        @Autowired
        StudentService studentService;
    
        @RequestMapping("/getAllQuestionWithStudent")
        public List<QuestionStudentVO> getAllQuestionWithStudent() {
            List<QuestionStudentVO> questionStudent = questionService.getQuestionStudent();
            if (questionStudent == null) {
                return Collections.emptyList();
            }
            return questionStudent;
        }
    
        @RequestMapping("/getStudentNameByQuestionId")
        public List<String> getStudentNameById(Long id) {
            return questionService.getStudentNameByQuestionId(id);
        }
    
        @RequestMapping("/getStudentNamesByQuestionIds")
        public List<String> getStudentNamesByQuestionIds(Long[] ids) {
            List<Long> questionIds = Arrays.asList(ids);
            return questionService.getStudentNamesByQuestionIds(questionIds);
        }
    }

## **测试** ##

**postman访问：**[http://localhost:8080/common/getAllQuestionWithStudent][http_localhost_8080_common_getAllQuestionWithStudent]

postman结果

[
        {
            "id": 1001,
            "studentId": 1,
            "name": null,
            "points": 201,
            "content": "this is question content",
            "value": 10
        },
        {
            "id": 1002,
            "studentId": 2,
            "name": null,
            "points": 100,
            "content": "this is question content",
            "value": 30
        }
    ]

后端结果

Creating a new SqlSession
    SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@597f87ec] was not registered for synchronization because synchronization is not active
    JDBC Connection [HikariProxyConnection@1471701683 wrapping com.mysql.cj.jdbc.ConnectionImpl@7b7782db] will not be managed by Spring
    ==>  Preparing: SELECT t_question.*,t_student.`name`,t_student.points FROM t_question,t_student WHERE t_question.student_id=t_student.id 
    ==> Parameters: 
    <==    Columns: id, student_id, content, value, name, points
    <==        Row: 1001, 1, this is question content, 10, Iron Man, 201
    <==        Row: 1002, 2, this is question content, 30, Jarvis, 100
    <==      Total: 2
    Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@597f87ec]

**postman访问：**[http://localhost:8080/common/getStudentNameByQuestionId?id=1][http_localhost_8080_common_getStudentNameByQuestionId_id_1]

后端结果

Creating a new SqlSession
    SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@427b93c6] was not registered for synchronization because synchronization is not active
    JDBC Connection [HikariProxyConnection@1287419385 wrapping com.mysql.cj.jdbc.ConnectionImpl@7b7782db] will not be managed by Spring
    ==>  Preparing: SELECT t_student.name FROM t_question,t_student WHERE t_question.student_id = ? AND t_question.student_id=t_student.id 
    ==> Parameters: 1(Long)
    <==    Columns: name
    <==        Row: Iron Man
    <==      Total: 1
    Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@427b93c6]

postman结果

[
        "Iron Man"
    ]

**postman访问：**[http://localhost:8080/common/getStudentNamesByQuestionIds?ids=1,2][http_localhost_8080_common_getStudentNamesByQuestionIds_ids_1_2]

后端结果

Creating a new SqlSession
    SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@63dc1476] was not registered for synchronization because synchronization is not active
    JDBC Connection [HikariProxyConnection@1830549117 wrapping com.mysql.cj.jdbc.ConnectionImpl@7b7782db] will not be managed by Spring
    ==>  Preparing: SELECT t_student.name FROM t_question,t_student WHERE (t_question.student_id IN (?,?)) AND t_question.student_id=t_student.id 
    ==> Parameters: 1(Long), 2(Long)
    <==    Columns: name
    <==        Row: Iron Man
    <==        Row: Jarvis
    <==      Total: 2
    Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@63dc1476]

postman结果

[
        "Iron Man",
        "Jarvis"
    ]

# 单表分页 #

**其他网址**

[Mybatis-Plus官网（分页）][Mybatis-Plus]  
[Mybatis Plus 使用详解 - 六层楼 - 博客园][Mybatis Plus _ - _ -]

## 代码 ##

**mapper**

**Service**

package com.example.service;
    
    import com.baomidou.mybatisplus.extension.service.IService;
    import com.example.entity.Student;
    
    public interface StudentService extends IService<Student> {
    }

package com.example.service.impl;
    
    import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
    import com.example.entity.Student;
    import com.example.mapper.StudentMapper;
    import com.example.service.StudentService;
    import org.springframework.stereotype.Service;
    
    @Service
    public class StudentServiceImpl extends ServiceImpl<StudentMapper, Student> implements StudentService {
    }

**Controller**

import com.baomidou.mybatisplus.core.metadata.IPage;
    import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
    
    @RestController
    @RequestMapping("/common")
    public class CommonController {
        @Autowired
        QuestionService questionService;
    
        @Autowired
        StudentService studentService;
    
        @RequestMapping("/getAllStudent")
        public IPage<Student> getAllStudent(Page<Student> page) {
            // 如果查出来为空，会返回入参page里边的数据，比如：current，size等。不需要自己判空。
            return studentService.page(page,
                        new LambdaQueryWrapper<Student>().orderByDesc(Student::getName)
                    );
        }
    
        @RequestMapping("/getAllStudentByName")
        public IPage<Student> getAllStudentByName(Page<Student> page) {
            // 如果查出来为空，会返回入参page里边的数据，比如：current，size等。不需要自己判空。
            return studentService.lambdaQuery().eq(Student::getName, "Jarvis").page(page);
        }
    
        @RequestMapping("/getAllStudentByNameNo")
        public IPage<Student> getAllStudentByNameNo(Page<Student> page) {
            // 如果查出来为空，会返回入参page里边的数据，比如：current，size等。不需要自己判空。
            return studentService.lambdaQuery().eq(Student::getName, "NO NO").page(page);
        }
    
    }

## **测试** ##

postman访问：[http://localhost:8080/common/getAllStudent][http_localhost_8080_common_getAllStudent]

**使用第1条（无条件，会查出所有）**

postman结果

{
        "records": [
            {
                "id": 1,
                "name": "Iron Man",
                "points": 201
            },
            {
                "id": 2,
                "name": "Jarvis",
                "points": 100
            },
            {
                "id": 3,
                "name": "Tony",
                "points": 300
            }
        ],
        "total": 3,
        "size": 10,
        "current": 1,
        "orders": [],
        "optimizeCountSql": true,
        "hitCount": false,
        "searchCount": true,
        "pages": 1
    }

后端结果

Creating a new SqlSession
    SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@5810d535] was not registered for synchronization because synchronization is not active
    JDBC Connection [HikariProxyConnection@1456943175 wrapping com.mysql.cj.jdbc.ConnectionImpl@61b976ac] will not be managed by Spring
    JsqlParserCountOptimize sql=SELECT  id,name,points  FROM t_student
    ==>  Preparing: SELECT COUNT(1) FROM t_student 
    ==> Parameters: 
    <==    Columns: COUNT(1)
    <==        Row: 3
    ==>  Preparing: SELECT id,name,points FROM t_student LIMIT ?,? 
    ==> Parameters: 0(Long), 10(Long)
    <==    Columns: id, name, points
    <==        Row: 1, Iron Man, 201
    <==        Row: 2, Jarvis, 100
    <==        Row: 3, Tony, 300
    <==      Total: 3
    Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@5810d535]

**使用第2条（指定条件，有匹配到的）：**[http://localhost:8080/common/getAllStudentByName?size=5&current=1][http_localhost_8080_common_getAllStudentByName_size_5_current_1]

postman结果

{
        "records": [
            {
                "id": 2,
                "name": "Jarvis",
                "points": 100
            }
        ],
        "total": 1,
        "size": 5,
        "current": 1,
        "orders": [],
        "optimizeCountSql": true,
        "hitCount": false,
        "searchCount": true,
        "pages": 1
    }

后端结果

Creating a new SqlSession
    SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6b8778dc] was not registered for synchronization because synchronization is not active
    JDBC Connection [HikariProxyConnection@594281656 wrapping com.mysql.cj.jdbc.ConnectionImpl@61b976ac] will not be managed by Spring
    JsqlParserCountOptimize sql=SELECT  id,name,points  FROM t_student 
     
     WHERE (name = ?)
    ==>  Preparing: SELECT COUNT(1) FROM t_student WHERE (name = ?) 
    ==> Parameters: Jarvis(String)
    <==    Columns: COUNT(1)
    <==        Row: 1
    ==>  Preparing: SELECT id,name,points FROM t_student WHERE (name = ?) LIMIT ?,? 
    ==> Parameters: Jarvis(String), 0(Long), 5(Long)
    <==    Columns: id, name, points
    <==        Row: 2, Jarvis, 100
    <==      Total: 1
    Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6b8778dc]

**使用第3条（指定条件，没有匹配到的）：**[http://localhost:8080/common/getAllStudentByNameNo][http_localhost_8080_common_getAllStudentByNameNo]

postman结果

{
        "records": [],
        "total": 0,
        "size": 10,
        "current": 1,
        "orders": [],
        "optimizeCountSql": true,
        "hitCount": false,
        "searchCount": true,
        "pages": 0
    }

后端结果

Creating a new SqlSession
    SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6418d8d0] was not registered for synchronization because synchronization is not active
    JDBC Connection [HikariProxyConnection@1158294948 wrapping com.mysql.cj.jdbc.ConnectionImpl@61b976ac] will not be managed by Spring
    JsqlParserCountOptimize sql=SELECT  id,name,points  FROM t_student 
     
     WHERE (name = ?)
    ==>  Preparing: SELECT COUNT(1) FROM t_student WHERE (name = ?) 
    ==> Parameters: NO NO(String)
    <==    Columns: COUNT(1)
    <==        Row: 0
    Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6418d8d0]

# 多表分页 #

**其他网址**

[最简单的 MyBatis Plus 的多表联接、分页查询实现方法\_IT小村-CSDN博客\_mybatis plus多表查询][MyBatis Plus _IT_-CSDN_mybatis plus]

## 代码 ##

**Mapper**

**Service**

package com.example.service;
    
    import com.baomidou.mybatisplus.core.metadata.IPage;
    import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
    import com.baomidou.mybatisplus.extension.service.IService;
    import com.example.entity.Question;
    import com.example.vo.QuestionStudentVO;
    
    import java.util.List;
    
    public interface QuestionService extends IService<Question> {
        IPage<QuestionStudentVO> getQuestionStudentPage (Page<QuestionStudentVO> page);
    }

package com.example.service.impl;
    
    import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
    import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
    import com.example.entity.Question;
    import com.example.mapper.QuestionMapper;
    import com.example.service.QuestionService;
    import com.example.vo.QuestionStudentVO;
    import org.springframework.stereotype.Service;
    
    import java.util.List;
    
    @Service
    public class QuestionServiceImpl extends ServiceImpl<QuestionMapper, Question> implements QuestionService {
        //下边的this.baseMapper都可以用自动注入的QuestionMapper替换
    
        @Override
        public Page<QuestionStudentVO> getQuestionStudentPage (Page<QuestionStudentVO> page) {
            return page.setRecords(this.baseMapper.getQuestionStudentPage(page));
        }
    }

**Controller**

## **测试** ##

postman访问：

[http://localhost:8080/common/getAllQuestionWithStudentByPage?current=1&size=2][http_localhost_8080_common_getAllQuestionWithStudentByPage_current_1_size_2]

postman结果（可见数组或List无法直接赋值。）

{
        "records": [
            {
                "id": 1001,
                "studentId": 1,
                "name": null,
                "points": 201,
                "content": "this is question content",
                "value": 10
            },
            {
                "id": 1002,
                "studentId": 2,
                "name": null,
                "points": 100,
                "content": "this is question content",
                "value": 30
            }
        ],
        "total": 2,
        "size": 2,
        "current": 1,
        "orders": [],
        "optimizeCountSql": true,
        "hitCount": false,
        "searchCount": true,
        "pages": 1
    }

后端结果

Creating a new SqlSession
    SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@46bd5ef7] was not registered for synchronization because synchronization is not active
    JDBC Connection [HikariProxyConnection@1676586413 wrapping com.mysql.cj.jdbc.ConnectionImpl@61b976ac] will not be managed by Spring
    JsqlParserCountOptimize sql=SELECT t_question.*,t_student.* FROM t_question,t_student WHERE t_question.student_id=t_student.id
    ==>  Preparing: SELECT COUNT(1) FROM t_question, t_student WHERE t_question.student_id = t_student.id 
    ==> Parameters: 
    <==    Columns: COUNT(1)
    <==        Row: 2
    ==>  Preparing: SELECT t_question.*,t_student.* FROM t_question,t_student WHERE t_question.student_id=t_student.id LIMIT ?,? 
    ==> Parameters: 0(Long), 2(Long)
    <==    Columns: id, student_id, content, value, id, name, points
    <==        Row: 1001, 1, this is question content, 10, 1, Iron Man, 201
    <==        Row: 1002, 2, this is question content, 30, 2, Jarvis, 100
    <==      Total: 2
    Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@46bd5ef7]

## **手动包装Page** ##

Mybatis Plus分页查询的重点在于Page这个包装类。上边的多表分页查询用了page.setRecords其实就是手动包装的。再把代码拿过来看一下

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
    
    @Service
    public class QuestionServiceImpl extends ServiceImpl<QuestionMapper, Question> implements QuestionService {
        @Override
        public Page<QuestionStudentVO> getQuestionStudentPage (Page<QuestionStudentVO> page) {
            return page.setRecords(this.baseMapper.getQuestionStudentPage(page));
        }
    }

**this.baseMapper.getQuestionStudentPage(page)**

这个执行完之后，会将page的total等进行赋值。然后外部的page.setRecords会将其返回值设置到page里边去。

# 排序 #

排序涉及到Page类的List<OrderItem> orders;成员，OrderItem定义如下：

public class OrderItem implements Serializable {
        private static final long serialVersionUID = 1L;
    
        //需要进行排序的字段
        private String column;
    
        // 是否正序排列，默认 true
        private boolean asc = true;
        ...
    }

## 前端指定排序 ##

**Controller**

**测试**

postman访问：[http://localhost:8080/common/getAllStudentInOrder?current=1&size=2][http_localhost_8080_common_getAllStudentInOrder_current_1_size_2]

postman的body

orders\[0\].column

orders\[0\].asc

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaXlpbmcwY2FuZ2xhbmc_size_16_color_FFFFFF_t_70][]

postman的结果

{
        "records": [
            {
                "id": 3,
                "name": "Tony",
                "points": 300
            },
            {
                "id": 2,
                "name": "Jarvis",
                "points": 100
            }
        ],
        "total": 3,
        "size": 2,
        "current": 1,
        "orders": [
            {
                "column": "name",
                "asc": false
            }
        ],
        "optimizeCountSql": true,
        "hitCount": false,
        "searchCount": true,
        "pages": 2
    }

后端结果

Creating a new SqlSession
    SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@551ee9d2] was not registered for synchronization because synchronization is not active
    JDBC Connection [HikariProxyConnection@726462971 wrapping com.mysql.cj.jdbc.ConnectionImpl@61b976ac] will not be managed by Spring
    JsqlParserCountOptimize sql=SELECT  id,name,points  FROM t_student
    ==>  Preparing: SELECT COUNT(1) FROM t_student 
    ==> Parameters: 
    <==    Columns: COUNT(1)
    <==        Row: 3
    ==>  Preparing: SELECT id, name, points FROM t_student ORDER BY name DESC LIMIT ?,? 
    ==> Parameters: 0(Long), 2(Long)
    <==    Columns: id, name, points
    <==        Row: 3, Tony, 300
    <==        Row: 2, Jarvis, 100
    <==      Total: 2
    Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@551ee9d2]

## 后端OrderItems排序 ##

@GetMapping("/page")
    public IPage<User> getUserPage(Page<User> page) {
        page.addOrder(OrderItem.desc("create_time"), OrderItem.asc("id"));
    	return UserService.page(page);
    }

## 后端Wrapper排序 ##

@GetMapping("/page")
    public IPage<User> getUserPage(Page<User> page) {
        LambdaQueryWrapper<User> queryWrapper = Wrappers.<User>lambdaQuery();
    	queryWrapper.orderByDesc(User::getCreateTime);
    	queryWrapper.orderByAsc(User::getId);
    	return UserService.page(page, queryWrapper);
    }

# 其他网址 #

[一文MyBatis-Plus快速入门 - 享智同行 - 博客园][MyBatis-Plus_ - _ -]  
[mybatis-plus的使用 ------ 进阶 - 简书][mybatis-plus_ ------ _ -]

[Mybatis-Plus--_--_IT_-CSDN]: https://knife.blog.csdn.net/article/details/120961924
[mybatis Plus]: https://www.shuzhiduo.com/A/A7zgPnGYJ4/
[http_localhost_8080_common_getAllQuestionWithStudent]: http://localhost:8080/common/getAllQuestionWithStudent
[http_localhost_8080_common_getStudentNameByQuestionId_id_1]: http://localhost:8080/common/getStudentNameByQuestionId?id=1
[http_localhost_8080_common_getStudentNamesByQuestionIds_ids_1_2]: http://localhost:8080/common/getStudentNamesByQuestionIds?ids=1,2
[Mybatis-Plus]: https://mybatis.plus/guide/page.html%C2%A0
[Mybatis Plus _ - _ -]: https://www.cnblogs.com/rever/p/10833596.html
[http_localhost_8080_common_getAllStudent]: http://localhost:8080/common/getAllStudent
[http_localhost_8080_common_getAllStudentByName_size_5_current_1]: http://localhost:8080/common/getAllStudentByName?size=5&current=1
[http_localhost_8080_common_getAllStudentByNameNo]: http://localhost:8080/common/getAllStudentByNameNo
[MyBatis Plus _IT_-CSDN_mybatis plus]: https://blog.csdn.net/larger5/article/details/82082819
[http_localhost_8080_common_getAllQuestionWithStudentByPage_current_1_size_2]: http://localhost:8080/common/getAllQuestionWithStudentByPage?current=1&size=2
[http_localhost_8080_common_getAllStudentInOrder_current_1_size_2]: http://localhost:8080/common/getAllStudentInOrder?current=1&size=2
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaXlpbmcwY2FuZ2xhbmc_size_16_color_FFFFFF_t_70]: /images/20220828/b1290cef0eeb4ffca7a73fbffd91d7e5.png
[MyBatis-Plus_ - _ -]: https://www.cnblogs.com/AIThink/p/10872364.html
[mybatis-plus_ ------ _ -]: https://www.jianshu.com/p/a4d5d310daf8