Use tkmapper to add, delete, modify and query

0. tkMapper introduce

1. tkMapper It's just one. MyBatis plug-in unit , Is in MyBatis Provides a lot of tools based on , Make development simple , Improve development efficiency .
2. Introduce dependencies ：

   <dependency>
      <groupId>tk.mybatis</groupId>
      <artifactId>mapper-spring-boot-starter</artifactId>
      <version>${tk.mybatis.version}</version>
   </dependency>
   

3. Create an entity class that matches the database table , Such as ：

   @Data
   @Builder
   @NoArgsConstructor
   @AllArgsConstructor
   public class StudentInfo {
         
     
         @Id
         private Long id;
      
         /** *  full name  */
         private String name;
      
         /** *  cell-phone number  */
         private String mobile;
      
         /** *  Student number  */
         private String studentId;
      
         /** *  Class number  */
         private String classId;
      
         /** *  Creation time  */
         private Date ctime;
      
         /** *  Update time  */
         private Date mtime;
      
         /** *  Delete logo  0: Not delete  1： Delete  */
         private Integer deleted_status;
   }
   

4. establish mapper Interface ：

   public interface StudentInfoMapper<StudentInfo> extends Mapper<StudentInfo>, MySqlMapper<StudentInfo>, BatchMapper<StudentInfo>, GroupMapper<StudentInfo> {
         
   
   }
   

5. Next, I will briefly introduce several commonly used tkMapper How to add, delete, modify, and search , There are many things that have not been introduced , You can move tkMapper Official documents for more detailed information ～

1. insert data

1.1. insert

Use insert, If the value of a certain item of data is null, Will be inserted directly into the corresponding column in the database table null, It is not recommended to use .

StudentInfo info = StudentInfo.builder()
  .name("Zhangsan")
  .mobile("12312341234")
  .build();

studentInfoMapper.insert(info);

For example, the above writing , The other fields of this record inserted into the database will be null;

1.2. insertSelective

Use insertSelective, If the value of a certain item of data is null, The default value set by the database table will be directly inserted into the corresponding column in the database table , Recommended .

StudentInfo info = StudentInfo.builder()
  .name("Zhangsan")
  .mobile("12312341234")
  .build();

studentInfoMapper.insertSelective(info);

For example, the above writing , The other fields of this record inserted into the database will be the default values of the database table ;

1.3. insertList

Use insertList, You can insert multiple records into the database table at one time .

List<StudentInfo> infoList = XXXX;

studentInfoMapper.insertList(infoList);

2. Query data

2.1. selectAll

Use selectAll, Directly query all data .

List<StudentInfo> infoList = studentInfoMapper.selectAll();

2.2 selectByPrimaryKey

Use selectByPrimaryKey, Query according to the primary key .

StudentInfo info = studentInfoMapper.selectByPrimaryKey(15);

2.3. Use selectByExample / selectOneByExample Query conditions

See another article ：tkMapper The use of Weekend Join conditions to query conditions

2.4. Paging query

See another article ：MyBatis The use of PageHelper The plug-in performs paging queries

3. Update data

3.1. updateByExampleSelective

If we want to update the student information according to the student number , Then we can use the following methods ：

Weekend<StudentInfo> weekend = Weekend.of(StudentInfo.class);
WeekendCriteria<StudentInfo, Object> weekendCriteria = weekend.weekendCriteria();
weekendCriteria.andEqualTo(StudentInfo::getStudentId, studentId);
weekendCriteria.andEqualTo(StudentInfo::getDeletedStatus, 0);
StudentInfo info = studentInfoMapper.selectOneByExample(weekend);
if (Objects.isNull(info)) {
    
    throw new  Here you can customize the exception throw ;
}
StudentInfo infoNeedToUpdate =  Data that needs to be updated ;
studentInfoMapper.updateByExampleSelective(infoNeedToUpdate, weekend);

Check first , Ensure that the data to be updated exists , Update again ;

4. Delete data

Generally in business , Physical deletion is prohibited , All of our commonly used logical deletions are often just updates deletedStatus Status as “ deleted ” that will do , The method of updating data should be used here , I won't repeat ;