sql - Fill values in SQL Server
问题描述
I have a table projects
, and a log of changes to those project status
columns: OldStatus
and NewStatus
.
I would like to calculate the status of a project for the periods below:
Project_ID Period OldStatus NewStatus
123 201705 NULL NULL
123 201706 NULL NULL
123 201707 A D
123 201708 NULL NULL
123 201709 NULL NULL
123 201710 NULL NULL
123 201711 D A
123 201712 NULL NULL
123 201713 NULL NULL
And my ideal output:
Project_ID Period Status
123 201705 A
123 201706 A
123 201707 D
123 201708 D
123 201709 D
123 201710 D
123 201711 A
123 201712 A
123 201713 A
(If no prior status found, it is A)
Test data:
SELECT '123' AS [Project_ID], 201603 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201604 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201605 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201606 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201607 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201608 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201609 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201610 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201611 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201612 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201613 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201701 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201702 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201703 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201704 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201705 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201706 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201707 AS [Period], 'A' AS [OldStatus], 'D' AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201708 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201709 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201710 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201711 AS [Period], 'D' AS [OldStatus], 'A' AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201712 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201713 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201801 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201802 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201803 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201804 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201805 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201806 AS [Period], 'A' AS [OldStatus], 'D' AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201807 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201808 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201809 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201810 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201811 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201812 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201813 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201814 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201815 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201816 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201901 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201902 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201903 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '123' AS [Project_ID], 201904 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '321' AS [Project_ID], 201705 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
UNION ALL
SELECT '321' AS [Project_ID], 201706 AS [Period], 'A' AS [OldStatus], 'I' AS [NewStatus]
UNION ALL
SELECT '321' AS [Project_ID], 201707 AS [Period], NULL AS [OldStatus], NULL AS [NewStatus]
Edit
My final query based on answer by @Gordon Linoff below.
I introduced a second table: project_main, which includes the current project status. This is required in cases where no history is recorded.
SELECT
p.project_id,
p.period,
COALESCE(p.new_status, pprev.new_status, pnext.old_status, crrnt.status) AS status
FROM projects p OUTER APPLY
(SELECT TOP (1) old_status
FROM projects p2
WHERE p2.project_id = p.project_id AND p2.period >= p.period
AND old_status IS NOT NULL
ORDER BY p2.period DESC
) pnext OUTER APPLY
(SELECT TOP (1) new_status
FROM projects p2
WHERE p2.project_id = p.project_id AND p2.period <= p.period
AND new_status IS NOT NULL
ORDER BY p2.period DESC
) pprev OUTER APPLY
(SELECT TOP (1) Status
FROM project_main p3 -- The current project status is stored here
WHERE PR.project_id = p3.project_id) crrnt
ORDER BY Period ASC;
解决方案
嗯,您真正想要的是 and 上的选项IGNORE NULLS
,但 SQL Server 不支持该选项。LAG()
LEAD()
select p.project_id, p.period,
coalesce(p.new_status, pnext.old_status, pprev.new_status, 'A') as status
from projects p outer apply
(select top (1) old_status
from projects p2
where p2.project_id = p.project_id and
p2.period >= p.period and
p2.old_status is not null
order by p2.period asc
) pnext outer apply
(select top (1) new_status
from projects p2
where p2.project_id = p.project_id and
p2.period <= p.period and
p2.new_status is not null
order by p2.period desc
) pprev;
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