Question

我有这样的表，

REPORT_ID         USER_ID     ACTION_TYPE ACTION_START            
----------------- ----------- ----------- ----------------------- 
20122511549-621   621         OPEN        2012-02-05 11:05:49.000 
20122511549-621   621         CLOSE       2012-02-19 10:53:28.000 
20132121098-621   621         OPEN        2013-02-12 10:09:08.807 
20132121098-621   621         ACCEPT      2013-02-12 11:16:17.167 
20132121098-621   621         COMMENT     2013-02-12 12:20:17.167 
20132121098-621   621         CLOSE       2013-03-22 16:20:17.167 
201321814390-621  621         OPEN        2013-02-18 14:39:00.157 
201322010148-707  707         OPEN        2013-02-20 10:01:48.693 
201322010148-707  707         RETRIEVE    2013-10-29 13:22:05.017

我正在尝试的没有太大成功的是从上一行到当前行选择ACTION_START作为prev_action_start

条件：

当所有行的REPORT_ID = REPORT_ID时，除了ACTION_TYPE ='OPEN'时，当前行为prev_action_start应为ACTION_START 看起来像这样：

REPORT_ID         USER_ID     ACTION_TYPE ACTION_START            prev_action_start 
----------------- ----------- ----------- ----------------------- ------------------------
20122511549-621   621         OPEN        2012-02-05 11:05:49.000 2012-02-05 11:05:49.000
20122511549-621   621         CLOSE       2012-02-19 10:53:28.000 2012-02-05 11:05:49.000
20132121098-621   621         OPEN        2013-02-12 10:09:08.807 2013-02-12 10:09:08.807
20132121098-621   621         ACCEPT      2013-02-12 11:16:17.167 2013-02-12 10:09:08.807
20132121098-621   621         COMMENT     2013-02-12 12:20:17.167 2013-02-12 11:16:17.167
20132121098-621   621         CLOSE       2013-03-22 16:20:17.167 2013-02-12 12:20:17.167
201321814390-621  621         OPEN        2013-02-18 14:39:00.157 2013-02-18 14:39:00.157
201322010148-707  707         OPEN        2013-02-20 10:01:48.693 2013-02-20 10:01:48.693
201322010148-707  707         RETRIEVE    2013-10-29 13:22:05.017 2013-02-20 10:01:48.693

如果any1可以帮助我会感激吗？

Answer 1

在SQL Server 2012中，您可以使用lag()功能。在早期版本中，您需要执行显式连接或相关子查询。我发现后者最容易遵循：

select t.*,
       (case when Action_Type = 'Open' then Action_Start else prev1
        end) as prev_action_start
from (select t.*,
             (select top 1 Action_Start
              from table t2
              where t2.ReportId = t.ReportId and
                    t2.Action_Start < t.Action_Start
              order by Action_Start desc
             ) as prev1
      from table t
     ) t;

您实际上可以将子查询放在case语句中（消除子查询），但我认为将逻辑分成两部分会更清楚。

选择上一行日期到当前行日期

1 个答案: