我在编写查询时遇到困难。查询如下所示:
SELECT case when Year(LOAN_START_DATE) = 2010 then
max(LOAN_RES_BANK_CODE) else 0 end as '2010',
case when Year(LOAN_START_DATE) = 2011 then
max(LOAN_RES_BANK_CODE) else 0 end as '2011',
case when Year(LOAN_START_DATE) = 2012 then
max(LOAN_RES_BANK_CODE) else 0 end as '2012',
case when Year(LOAN_START_DATE) = 2013 then
max(LOAN_RES_BANK_CODE) else 0 end as '2013',
case when Year(LOAN_START_DATE) = 2014 then
max(LOAN_RES_BANK_CODE) else 0 end as '2014',
case when Year(LOAN_START_DATE) = 2015 then
max(LOAN_RES_BANK_CODE) else 0 end as '2015'
from LLOAN l
inner join LACMSTR c on c.ACCT_NUMBER = l.LOAN_ACCT_1 and c.SourceID = l.SourceID
where l.SourceID = 1
and c.ACCT_NUMBER = 1065
group by LOAN_START_DATE
这给出了以下输出:
2010 2011 2012 2013 2014 2015
----------------------------------
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
1 0 0 0 0 0
0 0 3 0 0 0
0 0 0 2 0 0
0 0 0 2 0 0
0 0 0 0 2 0
我希望输出只有一行，如下所示:
2010 2011 2012 2013 2014 2015
----------------------------------
1 0 3 2 2 0
我找到了一种方法来做到这一点，但它确实是一个丑陋且缓慢(相对而言)的查询:
select (select ISNULL(max(LOAN_RES_BANK_CODE),0)
from PfeDs.dbo.LLOAN t1, pfeds.dbo.LACMSTR t2
where t1.SourceID = t2.SourceID
and t2.SourceID = 1
and ACCT_NUMBER = LOAN_ACCT_1
and ACCT_NUMBER = 1065
and year(LOAN_START_DATE) = 2010) as '2010',
(select ISNULL(max(LOAN_RES_BANK_CODE),0)
from PfeDs.dbo.LLOAN t1, pfeds.dbo.LACMSTR t2
where t1.SourceID = t2.SourceID
and t2.SourceID = 1
and ACCT_NUMBER = LOAN_ACCT_1
and ACCT_NUMBER = 1065
and year(LOAN_START_DATE) = 2011) as '2011',
(select ISNULL(max(LOAN_RES_BANK_CODE),0)
from PfeDs.dbo.LLOAN t1, pfeds.dbo.LACMSTR t2
where t1.SourceID = t2.SourceID
and t2.SourceID = 1
and ACCT_NUMBER = LOAN_ACCT_1
and ACCT_NUMBER = 1065
and year(LOAN_START_DATE) = 2012) as '2012',
(select ISNULL(max(LOAN_RES_BANK_CODE),0)
from PfeDs.dbo.LLOAN t1, pfeds.dbo.LACMSTR t2
where t1.SourceID = t2.SourceID
and t2.SourceID = 1
and ACCT_NUMBER = LOAN_ACCT_1
and ACCT_NUMBER = 1065
and year(LOAN_START_DATE) = 2013) as '2013',
(select ISNULL(max(LOAN_RES_BANK_CODE),0)
from PfeDs.dbo.LLOAN t1, pfeds.dbo.LACMSTR t2
where t1.SourceID = t2.SourceID
and t2.SourceID = 1
and ACCT_NUMBER = LOAN_ACCT_1
and ACCT_NUMBER = 1065
and year(LOAN_START_DATE) = 2014) as '2014',
(select ISNULL(max(LOAN_RES_BANK_CODE),0)
from PfeDs.dbo.LLOAN t1, pfeds.dbo.LACMSTR t2
where t1.SourceID = t2.SourceID
and t2.SourceID = 1
and ACCT_NUMBER = LOAN_ACCT_1
and ACCT_NUMBER = 1065
and year(LOAN_START_DATE) = 2015) as '2015'
SQL不是我的强项。我应该以什么方式更改原始查询以获得我正在寻找的结果。我使用的是 SQL Server 2014。
---------------------编辑------------------
Jarlh 给出了一个很好的解决方案，以下查询给出了正确的输出:
select max(J10) as '2010', max(J11) as '2011', max(J12) '2012', max(J13) as '2013', max(J14) as '2014', max(J15) as '2015'
from (
SELECT case when Year(LOAN_START_DATE) = 2010 then max(LOAN_RES_BANK_CODE) else 0 end as J10,
case when Year(LOAN_START_DATE) = 2011 then max(LOAN_RES_BANK_CODE) else 0 end as J11,
case when Year(LOAN_START_DATE) = 2012 then max(LOAN_RES_BANK_CODE) else 0 end as J12,
case when Year(LOAN_START_DATE) = 2013 then max(LOAN_RES_BANK_CODE) else 0 end as J13,
case when Year(LOAN_START_DATE) = 2014 then max(LOAN_RES_BANK_CODE) else 0 end as J14,
case when Year(LOAN_START_DATE) = 2015 then max(LOAN_RES_BANK_CODE) else 0 end as J15
from pfeds.dbo.LLOAN l
inner join PfeDs.dbo.LACMSTR c on c.ACCT_NUMBER = l.LOAN_ACCT_1 and c.SourceID = l.SourceID
where l.SourceID = 1
and c.ACCT_NUMBER = 1065
group by LOAN_START_DATE) as test
最佳答案
使用原始查询作为派生表，然后MAX列:
select MAX('2010'), ...
from (
SELECT case when Year(LOAN_START_DATE) = 2010 then
max(LOAN_RES_BANK_CODE) else 0 end as '2010',
...
)
关于SQL Case When - 从输出中删除 'empty' 行，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/30072631/