Tkmapper uses weekend splicing conditions to query conditions

0. introduce

We use it here StudentInfo Entity classes ：

@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;
}

1. andEqualTo

Use andEqualTo sentence , It is equivalent to using where Field name = Certain value Of SQL sentence

If we want to inquire about the class number 12345678 Of the students , It can be written like this ：

Weekend<StudentInfo> weekend = Weekend.of(StudentInfo.class);
WeekendCriteria<StudentInfo, Object> weekendCriteria = weekend.weekendCriteria();
weekendCriteria.andEqualTo(StudentInfo::getClassId, "12345678");
weekendCriteria.andEqualTo(StudentInfo::getdeletedStatus, 0);
List<StudentInfo> infoList = studentInfoMapper.selectByExample(weekend);

Because it is expected to be able to query the information of multiple students , So you should use selectByExample, And use List To receive the return message ;

2. andIn

Use andIn sentence , It is equivalent to using where Field name in A value range Of SQL sentence

If we want to number in the student class 12345678 On the basis of , The student number is found to be 0001、0002 and 0003 Classmate , Then you can write like this ：

Weekend<StudentInfo> weekend = Weekend.of(StudentInfo.class);
WeekendCriteria<StudentInfo, Object> weekendCriteria = weekend.weekendCriteria();
weekendCriteria.andEqualTo(StudentInfo::getClassId, "12345678");
List<String> studentIdList = Arrays.asList("0001", "0002", "0003");
weekendCriteria.andIn(StudentInfo::getStudentId, studentIdList);
weekendCriteria.andEqualTo(StudentInfo::getdeletedStatus, 0);
List<StudentInfo> infoList = studentInfoMapper.selectByExample(weekend);

3. andNotEqualTo

It happens to be with andEqualTo contrary ;

4. andNotIn

It happens to be with andIn contrary ;

5. andGreaterThanOrEqualTo

seeing the name of a thing one thinks of its function , This is greater than or equal to , It can also be used to filter the data according to the modification date , It is written as follows ：

weekendCriteria.andGreaterThanOrEqualTo(StudentInfo::getMtime, DateUtils.transferString2Date(LocalDate.now().toString()));

among ,DateUtils.transferString2Date Methods can refer to another article of mine ： take String To date, Convenient and quick ;

6. andLike

have access to andLike Fuzzy query , But be careful , Fuzzy query will scan the whole table , Slow speed , It is easy to cause slow queries （ About slow queries , You can refer to another article of mine ： What is slow query ？ How to optimize ？）;

If we want to find all names with red The information of my classmates , It can be written like this ：

Weekend<StudentInfo> weekend = Weekend.of(StudentInfo.class);
WeekendCriteria<StudentInfo, Object> weekendCriteria = weekend.weekendCriteria();
weekendCriteria.andLike(StudentInfo::getName, "%" + " red " + "%");
weekendCriteria.andEqualTo(StudentInfo::getdeletedStatus, 0);
List<StudentInfo> infoList = studentInfoMapper.selectByExample(weekend);

If there are a lot of fuzzy searches in the database 、 Text matching , Consider making ElasticSearch,ElasticSearch It's a Distributed 、 High performance 、 High availability 、 Telescopic 、RESTful style Search and data analysis engine .

7. summary

When there are many query conditions , We can flexibly put all conditions together ,tkMapper Let's avoid handwriting to the greatest extent SQL sentence , Greatly improved our development efficiency .