MyBatisPlus查询方法selectById、selectOne、selectBatchIds、selectByMap、selectPage的使用

╰半夏微凉° 2023-10-18 17:30 16阅读 0赞

## 场景 ##

项目搭建专栏：

[https://blog.csdn.net/BADAO\_LIUMANG\_QIZHI/column/info/37194][https_blog.csdn.net_BADAO_LIUMANG_QIZHI_column_info_37194]

基础搭建：

[https://blog.csdn.net/BADAO\_LIUMANG\_QIZHI/article/details/89407994][https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_89407994]

## 实现 ##

### selectById查询 ###

/***
      * 通用查询操作  通过ID查询
      */
     @Test
     public void testCommomSelectById() {
      Employee employee=employeeMapper.selectById(1);
      System.out.println("*******************"+employee);
     }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70][]![Image 1][]

### selectOne查询 ###

/***
      * 通用查询操作 selectOne 最多只能查到一个
      */
     @Test
     public void testCommomSelectOne() {
      Employee employee = new Employee();
      employee.setId(3);
      employee.setName("气质");
      Employee employeeresult=employeeMapper.selectOne(employee);
      System.out.println("*******************"+employeeresult);
     }

![Image 1][]![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1][]

### selectBatchIdsvc查询 ###

/***
      * 通用查询操作 selectBatchIds 通过多个ID进行查询
      */
     @Test
     public void testCommomSelectBatchIds() {
      List<Integer> idList = new ArrayList<Integer>();
      idList.add(1);
      idList.add(2);
      idList.add(3);
      List<Employee>employeeList=employeeMapper.selectBatchIds(idList);
      System.out.println("*******************"+employeeList);
      for (Employee employee : employeeList) {
       System.out.println(employee.getName());
      }
     }

![Image 1][]![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2][]

### selectbyMap查询 ###

/***
      * 通用查询操作 selectByMap  map要写列名条件 不能是实体属性名
      */
     @Test
     public void testCommomSelectByMap() {
      Map<String, Object> columnMap = new HashMap<String, Object>();
      columnMap.put("name", "气质");
      columnMap.put("gender", "0");
      List<Employee> employeeList=employeeMapper.selectByMap(columnMap);
      System.out.println("*******************"+employeeList);
      for (Employee employee : employeeList) {
       System.out.println(employee.getName());
      }
     }

![Image 1][]![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 3][]

### selectByPage查询 ###

分页查询，第二个参数为条件构造器这里置为空。

/***
      * 通用查询操作 selectByPage
      */
     @Test
     public void testCommomSelectByPage() {
      
      List<Employee> employeeList=employeeMapper.selectPage(new Page<Object>(2, 2), null);
      System.out.println("*******************"+employeeList);
      for (Employee employee : employeeList) {
       System.out.println(employee.getName());
      }
     }

![Image 1][]![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 4][]

## 源码下载 ##

[https://download.csdn.net/download/badao\_liumang\_qizhi/11133873][https_download.csdn.net_download_badao_liumang_qizhi_11133873]

[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_column_info_37194]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/column/info/37194
[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_89407994]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/89407994
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/2019042220005711.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[Image 1]: 
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20190422200113979.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20190422200130332.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20190422200154219.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 4]: https://img-blog.csdnimg.cn/20190422200213654.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[https_download.csdn.net_download_badao_liumang_qizhi_11133873]: https://download.csdn.net/download/badao_liumang_qizhi/11133873