Question

我有一张包含下列专栏的表格：

ID（int）AUTO_INCREMENT PRIMARY KEY
DOCTOR_ID（int）
PATIENT_IN_TIME（日期时间）
AVG_CHECKUP_TIME

我想用第2行PATIENT_IN_TIME减去第1行PATIENT_IN_TIME，并将结果以分钟为单位保存到AVG_CHECKUP_TIME。

假设表格中有5个条目。

|1|2|2018-03-22 02:49:51|NULL|

|2|2|2018-03-22 02:56:37|NULL|

所以我想找到两行的差异并保存最后一列中的分钟。所以，输出看起来像，

|1|2|2018-03-22 02:49:51|7|

|2|2|2018-03-22 02:56:37|NULL|

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Answer 1

create table tbl 
(
  id int auto_increment primary key, 
  doctor_id int, 
  patient_in_time datetime, 
  avg_checkup_time datetime
);

insert into tbl values
(1, 2, '2018-03-22 02:49:51', null),
(2, 2, '2018-03-22 02:56:37', null),
(3, 2, '2018-03-22 03:00:15', null),
(4, 2, '2018-03-22 03:03:37', null);

select t1.id, t1.doctor_id, t1.patient_in_time, 
       timestampdiff(minute, t1.patient_in_time, 
                      (select patient_in_time 
                       from tbl where id = t1.id +1)) diff
from tbl t1

id | doctor_id | patient_in_time     | diff
-: | --------: | :------------------ | ---:
 1 |         2 | 2018-03-22 02:49:51 |    6
 2 |         2 | 2018-03-22 02:56:37 |    3
 3 |         2 | 2018-03-22 03:00:15 |    3
 4 |         2 | 2018-03-22 03:03:37 | null

dbfiddle here

根据评论，如果订单由patient_in_time设置，那么您可以使用以这种方式返回下一行的标量子查询：

select t1.id,
       t1.doctor_id,
       t1.patient_in_time,
       timestampdiff(minute, 
                     t1.patient_in_time, 
                     (select   patient_in_time
                      from     tbl 
                      where    patient_in_time > t1.patient_in_time
                      order by patient_in_time asc
                      limit 1)) diff
from   tbl t1
order by patient_in_time

id | doctor_id | patient_in_time     | diff
-: | --------: | :------------------ | ---:
 1 |         2 | 2018-03-22 02:49:51 |    6
 2 |         2 | 2018-03-22 02:56:37 |    3
 3 |         2 | 2018-03-22 03:00:15 |    3
 4 |         2 | 2018-03-22 03:03:37 | null

dbfiddle here

如何在MySQL中找到连续行中日期的差异并分别更新表列？

1 个答案: