sql-server - 如何检查上一行的值

Question

以下是我表中的模型数据。

Data:
Date    Worked Hours    IsLate
8/1/2013    8:03:00     No
8/2/2013    10:52:00    No
8/3/2013    8:43:00     Yes
8/4/2013    9:26:00     No

如果前一天的工作时间等于 10 小时，则 IsLate 列将更新为“是”。如何计算前一行值是否等于 10 小时。

请帮帮我。

Answer 1

询问：

SQLFIDDLE示例

with table5
as (
SELECT Date,
       [Worked Hours],
       IsLate,
ROW_NUMBER() OVER (ORDER BY Date ASC, [Worked Hours] ASC) AS RowNumber1
FROM Table1 
)
SELECT t1.Date,
       t1.[Worked Hours],
       t1.IsLate,
       CASE WHEN LEFT(t2.[Worked Hours],2) = '10' 
            THEN 'Equal'
            ELSE 'Not Equal' END AS isequal
FROM table5 t1
LEFT JOIN table5 t2
ON t1.RowNumber1 - 1 = t2.RowNumber1

结果：

|                          DATE | WORKED HOURS | ISLATE |   ISEQUAL |
|-------------------------------|--------------|--------|-----------|
| August, 01 2013 00:00:00+0000 |      8:03:00 |     No | Not Equal |
| August, 02 2013 00:00:00+0000 |     10:52:00 |     No | Not Equal |
| August, 03 2013 00:00:00+0000 |      8:43:00 |    Yes |     Equal |
| August, 04 2013 00:00:00+0000 |      9:26:00 |     No | Not Equal |

如果您只想更新表，请使用：

SQLFIDDLE示例

UPDATE Table1
SET [IsLate] = ISNULL((SELECT TOP 1 CASE WHEN LEFT(t1.[Worked Hours],2) = '10' 
                                         THEN 'Equal'
                                         ELSE 'Not' END
                 FROM Table1 t1
                 WHERE t1.Date < Table1.Date
                 ORDER BY t1.Date DESC), 'Not')

结果：

|                          DATE | WORKED HOURS | ISLATE |
|-------------------------------|--------------|--------|
| August, 01 2013 00:00:00+0000 |      8:03:00 |    Not |
| August, 02 2013 00:00:00+0000 |     10:52:00 |    Not |
| August, 03 2013 00:00:00+0000 |      8:43:00 |  Equal |
| August, 04 2013 00:00:00+0000 |      9:26:00 |    Not |

Answer 2

IF 10 <= (SELECT DATEPART(hh, Worked_Hours) from Data)
Begin

Update Data set isLate = 'No'
where ..

End

Answer 3

update yourtable
set late='yes'
from yourtable
where
    (select top 1 datepart(hh,worked) 
           from yourtable t2 
           where t2.workdate<yourtable.workdate order by workdate desc)=10

Answer 4

这个怎么样？

declare @d table (WorkedDate date,WorkedHours time,IsLate varchar(10));

insert @d select '8/1/2013','8:03',null;
insert @d select '8/2/2013','10:52',null;
insert @d select '8/3/2013','8:43',null;
insert @d select '8/4/2013','9:26',null;

update @d set IsLate=case when exists (select WorkedHours from @d p where p.WorkedDate=dateadd(day,-1,d.WorkedDate) and WorkedHours>'10:00') then 'Yes' else 'No' end
from @d d;


select * from @d;