我有一个包含几列的表格。我想填充值以替换空值,但是这会因其他列而变得复杂。以下是我的样本:
date id1 id2 id3 id4 value
1/1/14 a 1 1 1 1.2
1/2/14 a 1 1 1 NULL
1/8/14 a 1 1 1 2.3
1/1/14 a 2 1 1 10.1
1/2/14 a 2 1 1 12.3
1/17/14 a 2 1 1 NULL
1/18/14 a 2 1 1 10.8
1/1/14 a 2 3 1 100.3
1/2/14 a 2 3 1 NULL
1/6/14 a 2 3 1 110.4
我想复制value
,而值仍然在id1-4的“组”内。例如,就要复制的值而言,所有“A-1-1-1”应与“a-2-1-1”隔离。我需要的输出是:
date id1 id2 id3 id4 value
1/1/14 a 1 1 1 1.2
1/2/14 a 1 1 1 1.2
1/8/14 a 1 1 1 2.3
1/1/14 a 2 1 1 10.1
1/2/14 a 2 1 1 12.3
1/17/14 a 2 1 1 12.3
1/18/14 a 2 1 1 10.8
1/1/14 a 2 3 1 100.3
1/2/14 a 2 3 1 100.3
1/6/14 a 2 3 1 110.4
我可以使用CROSS APPLY
为单个列执行此操作,但多列的语法让我感到困惑。生成临时数据的SQL是:
DECLARE @test TABLE
(
date DATETIME
,id1 VARCHAR(1)
,id2 INT
,id3 INT
,id4 INT
,value FLOAT
)
INSERT INTO @test VALUES
('2014-01-01','a','1','1','1','1.2')
,('2014-01-02','a','1','1','1',NULL)
,('2014-01-08','a','1','1','1','2.3')
,('2014-01-01','a','2','1','1','10.1')
,('2014-01-02','a','2','1','1','12.3')
,('2014-01-17','a','2','1','1',NULL)
,('2014-01-18','a','2','1','1','10.8')
,('2014-01-01','a','2','3','1','100.3')
,('2014-01-02','a','2','3','1',NULL)
,('2014-01-06','a','2','3','1','110.4')
;
SELECT * FROM @test;
答案 0 :(得分:2)
您可以使用apply
:
select t.*, coalesce(t.value, tprev.value) as value
from @test t outer apply
(select top 1 value
from @test t2
where t2.id1 = t.id1 and t2.id2 = t.id2 and t2.id3 = t.id3 and t2.id4 = t.id4 and
t2.date < t.date and t2.value is not null
order by t2.date desc
) tprev;