Mysql DateTime 查询问题解析

 
 public static final LocalTime MAX;
 
 public static final LocalDateTime MAX = LocalDateTime.of(LocalDate.MAX, LocalTime.MAX);

 LocalDateTime now = LocalDateTime.now();
 System.out.println(now);

 @Override
 public long millis() {
     return System.currentTimeMillis();
 }
 @Override
 public Instant instant() {
     return Instant.ofEpochMilli(millis());
 }

 drop table MQst1;
 create table mqst1
 (
     id         int      null,
     createtime datetime(0) null
 );
 INSERT INTO test_schema.mqst1 (id, createtime) VALUES (1, '2021-10-01 21:08:08.123');
 INSERT INTO test_schema.mqst1 (id, createtime) VALUES (1, '2021-10-01 23:59:59.567');
 INSERT INTO test_schema.mqst1 (id, createtime) VALUES (2, '2021-10-02 00:00:00.000');
 select *
 from mqst1
 where createtime >= '2021-10-01 00:00:00'  and createtime <= '2021-10-01 23:59:59.999999';
 select *
 from mqst1
 where createtime >= '2021-10-01 00:00:00' and createtime <= '2021-10-01 23:59:59.9999995';

 createtime datetime(2) null

 System.out.println(LocalDateTime.of(LocalDate.now(), LocalTime.MAX).withNano(999999000));