mybatisPlus动态sql语句 ${ew.sqlSegment}

这里主要是介绍通过MyBatis Plus使用${ew.sqlSegment}进行条件分页查询示例等，方便以后查阅！！！

一、简介

${ew.customSqlSegment}是MyBatis Plus提供的动态SQL语句拼接功能。

1、在使用MyBatis Plus进行数据库操作时，可以通过Wrapper对象来构建查询条件。Wrapper对象可以通过链式调用的方式动态添加查询条件，包括等于、大于、小于等各种条件。而${ew.customSqlSegment}就是Wrapper对象中自定义的SQL片段，可以灵活地根据业务需求进行动态拼接。

2、例如，在上述代码中，${ew.customSqlSegment}可以用于拼接额外的查询条件或者排序规则。具体的拼接逻辑可以通过在方法的参数中传入Wrapper对象来实现。

3、${ew.customSqlSegment}和${ew.sqlSegment}是什么？

${ew.customSqlSegment}在使用时，相当与 where + queryWrapper内的条件 ${ew.sqlSegment}相当于queryWrapper内的条件

二、分页条件查询

dao层

mapper-java文件

package com.wl.cloud.monitor.dao;

import com.wl.cloud.monitor.domain.StudentTest;

import com.baomidou.mybatisplus.core.conditions.Wrapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;

import com.baomidou.mybatisplus.core.metadata.IPage;

import com.baomidou.mybatisplus.core.toolkit.Constants;

import com.wl.cloud.monitor.support.vo.StudentTestVO;

import org.apache.ibatis.annotations.Mapper;

import org.apache.ibatis.annotations.Param;

import java.util.List;

/**

* test信息 Mapper接口

*

* @author wanglin

* @since 2024-03-21

*/

@Mapper

public interface StudentTestMapper extends BaseMapper {

/**

* 查询test信息

*

* @return

*/

List selectStudentTestList();

/**

* 分页

*

* @param page

* @param ew

* @return

*/

IPage getPage(IPage page, @Param(Constants.WRAPPER) Wrapper ew);

/**

* 列表

*

* @param ew

* @return

*/

List getList(@Param(Constants.WRAPPER) Wrapper ew);

/**

* 查询详情

*

* @param id

* @return

*/

StudentTestVO getById(@Param("id") String id);

}

dao-xml

mapper-xml文件

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

id, create_by, create_time, update_by, update_time, deleted, age, description, name, sex

server层

StudentTestServiceImpl

package com.wl.cloud.monitor.service.impl;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;

import com.baomidou.mybatisplus.core.metadata.IPage;

import com.baomidou.mybatisplus.core.toolkit.CollectionUtils;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;

import com.google.common.collect.Lists;

import com.wl.cloud.monitor.dao.StudentTestMapper;

import com.wl.cloud.monitor.domain.StudentTest;

import com.wl.cloud.monitor.service.StudentTestService;

import com.wl.cloud.monitor.support.dto.StudentTestDTO;

import com.wl.cloud.monitor.support.dto.query.StudentTestQueryDTO;

import com.wl.cloud.monitor.support.vo.StudentTestVO;

import com.wl.cloud.core.dto.DataStoreDTO;

import com.wl.cloud.core.utils.PageUtils;

import org.apache.commons.lang3.StringUtils;

import org.springframework.beans.BeanUtils;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.data.domain.Pageable;

import org.springframework.data.domain.Sort;

import org.springframework.stereotype.Service;

import org.springframework.transaction.annotation.Transactional;

import org.springframework.util.Assert;

import java.util.List;

import java.util.Objects;

import java.util.Set;

import java.util.stream.Collectors;

/**

* test信息 服务实现类

*

* @author wanglin

* @since 2024-03-21

*/

@Service

public class StudentTestServiceImpl implements StudentTestService {

@Autowired

private StudentTestMapper studentTestMapper;

@Transactional(readOnly = true)

@Override

public DataStoreDTO page(Pageable pageable, StudentTestQueryDTO queryDto) {

QueryWrapper queryWrapper = this.buildQuery(queryDto);

Page page = PageUtils.transferPage(pageable);

IPage result = this.studentTestMapper.getPage(page, queryWrapper);

return new DataStoreDTO(result.getTotal(), result.getRecords());

}

@Transactional(readOnly = true)

@Override

public List list(Sort sort, StudentTestQueryDTO queryDto) {

QueryWrapper queryWrapper = this.buildQuery(queryDto);

PageUtils.transferSort(queryWrapper, sort);

return this.studentTestMapper.getList(queryWrapper);

}

@Transactional(rollbackFor = Exception.class)

@Override

public void save(StudentTestDTO dto) {

// TODO 唯一性字段校验

dto.setId(null);

studentTestMapper.insert(this.transferEntity(null, dto));

}

@Transactional(rollbackFor = Exception.class)

@Override

public void update(StudentTestDTO dto) {

Assert.hasText(dto.getId(), "id不能为空");

// TODO 唯一性字段校验

StudentTest entity = studentTestMapper.selectById(dto.getId());

Assert.notNull(entity, "找不到id为 " + dto.getId() + " 的记录");

studentTestMapper.updateById(this.transferEntity(entity, dto));

}

@Transactional(rollbackFor = Exception.class)

@Override

public void delete(Set ids) {

if (CollectionUtils.isNotEmpty(ids)) {

studentTestMapper.deleteBatchIds(ids);

}

}

@Transactional(readOnly = true)

@Override

public StudentTestVO get(String id) {

Assert.hasText(id, "id不能为空");

StudentTest entity = studentTestMapper.selectById(id);

Assert.notNull(entity, "找不到id为 " + id + " 的记录");

return this.transferVo(entity);

}

private QueryWrapper buildQuery(StudentTestQueryDTO queryDto) {

QueryWrapper queryWrapper = new QueryWrapper<>();

if (Objects.nonNull(queryDto)) {

queryWrapper.lambda().eq(StringUtils.isNotBlank(queryDto.getId()), StudentTest::getId, queryDto.getId());

}

return queryWrapper;

}

private StudentTest transferEntity(StudentTest entity, StudentTestDTO dto) {

if (Objects.isNull(entity)) {

entity = new StudentTest();

}

BeanUtils.copyProperties(dto, entity);

return entity;

}

private List transferVo(List entities) {

if (CollectionUtils.isEmpty(entities)) {

return Lists.newArrayList();

}

List voList = entities.stream().map(entity -> {

StudentTestVO vo = new StudentTestVO();

BeanUtils.copyProperties(entity, vo);

return vo;

}).collect(Collectors.toList());

return voList;

}

private StudentTestVO transferVo(StudentTest entity) {

if (Objects.isNull(entity)) {

return null;

}

StudentTestVO vo = new StudentTestVO();

BeanUtils.copyProperties(entity, vo);

return vo;

}

}

关注林哥，持续更新哦！！！★,°:.☆(￣▽￣)/$:.°★ 。

参考阅读

评论可见，请评论后查看内容，谢谢！！！
 您阅读本篇文章共花了：