我如何匹配这些值以便比较它们

Question

我需要获取两个不同行的两个时间之间的日期差。我试图操纵这个 table 的 ID，但发现了死胡同。

table 看起来像这样：

ID      TimeIn       TimeOut     EmpId
 1      8.30am       12.30pm      usr1
 2      1.30pm       5.30pm       usr1

我需要得到第一行的TimeOut和第二行的Timein之间的时间差。

预期的输出应该是这样的：

EmpId LunchTime
usr1 1:00

1:00相当于1小时。

Answer 1

我怀疑你真正想问的是，"how do I match up the values in order to compare them"。一旦您拥有两个值，比较就很简单了，但是匹配行对就不那么简单了。查看这篇文章，了解如何解决类似问题的几乎精确的步骤：https://www.simple-talk.com/sql/t-sql-programming/solving-complex-t-sql-problems,-step-by-step/

Answer 2

以下是我的代码，在MYSQL中测试，供大家参考。

//EMP table content like below
id  TimeIn              TimeOut             EmpId
1   2015-03-21 09:00:00 2015-03-21 12:30:00 usr1
2   2015-03-21 13:30:00 2015-03-21 17:30:00 usr1
3   2015-03-21 08:00:00 2015-03-21 13:30:00 usr2
4   2015-03-21 14:00:00 2015-03-21 16:00:00 usr2
// find every empId TimeOut of first row and TimeIn of second row
SELECT id,TimeOut ,EmpId,
(select c.TimeIn from EMP  c where c.EmpId = a.EmpId and c.id > a.id limit 1) as 'TimeIn'
 from EMP a
//result as below
1   2015-03-21 12:30:00 usr1    2015-03-21 13:30:00
2   2015-03-21 17:30:00 usr1    NULL
3   2015-03-21 13:30:00 usr2    2015-03-21 14:00:00
4   2015-03-21 16:00:00 usr2    NULL
//find the timediff between TimeIn and TimeOut
select id,EmpId,timediff(TimeIn,TimeOut) as diff from 
(
  SELECT id,TimeOut ,EmpId,
  (select c.TimeIn from EMP  c where c.EmpId = a.EmpId and c.id > a.id limit 1) as 'TimeIn'
  from EMP a
) as tmp
// result as below
id  EmpId   diff
1   usr1    01:00:00
2   usr1    NULL
3   usr2    00:30:00
4   usr2    NULL

希望对您有所帮助。

我如何匹配这些值以便比较它们

how do I match up the values in order to compare them

sql

sql-server

datediff