How to unpivot table with dynamic columns - sql

Question

I'm trying to transpose a table called CHECK_CARD. It looks like this:
_________________________________________________________________
| anc_report_date | RiskSignal | group_company_attr |
|_____________________________|______________|____________________|
| 2019-01-01 00:00:00.0000000 | NoRiskSignal | 4894543 |
| 2016-07-01 00:00:00.0000000 | RiskSignal | 1242151 |
I want it to look like this:
____________________________________________________________________________
| anc_report_date |2019-01-01 00:00:00.0000000|2016-07-01 00:00:00.0000000|
|____________________|___________________________|___________________________|
| RiskSignal | NoRiskSignal | RiskSignal |
| group_company_attr | 1242151 | 1242151 |
The number of rows in anc_report_date is dynamic so what I'm trying to do is:
DECLARE #Column NVARCHAR(MAX)
SET #Column
= 'SELECT cc.anc_report_date
from CHECK_CARD cc
inner join CHECK_CARD chc on cc.group_company_attr=chc.group_company_attr and cc.anc_report_date<=chc.anc_report_date and chc.id=1832307
where cc.status=1'
exec sp_executesql #Column
Here I collect all column names.
DECLARE #Column NVARCHAR(MAX)
SET #Column
= 'SELECT cc.anc_report_date
from CHECK_CARD cc
inner join CHECK_CARD chc on cc.group_company_attr=chc.group_company_attr and cc.anc_report_date<=chc.anc_report_date and chc.id=1832307
where cc.status=1'
DECLARE #Transpose as NVARCHAR(MAX)
set #Transpose
= 'SELECT RiskSignal, group_company_attr
from CHECK_CARD
unpivot
(
kek
for anc_report_date in ('+ #Column +')
) u'
exec sp_executesql #Transpose;
But when I use it all together it returns "Incorrect syntax near the keyword 'SELECT'."
I think this line ('+ #Columns +') is the reason.
Any ideas?
PRINT #Transpose;
[2019-09-19 18:54:42] [S0001] SELECT RiskSignal, group_company_attr
[2019-09-19 18:54:42] from CHECK_CARD
[2019-09-19 18:54:42] unpivot
[2019-09-19 18:54:42] (
[2019-09-19 18:54:42] kek
[2019-09-19 18:54:42] for anc_report_date in (SELECT cc.anc_report_date
[2019-09-19 18:54:42] from CHECK_CARD cc
[2019-09-19 18:54:42] inner join CHECK_CARD chc on cc.group_company_attr=chc.group_company_attr and cc.anc_report_date<=chc.anc_report_date and chc.id=1832307 where cc.status=1)
[2019-09-19 18:54:42] ) u
[2019-09-19 18:54:42] completed in 3 ms

Answer 1

Made it, Thanks all!
DECLARE #cols AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #cols = STUFF((SELECT ',' + QUOTENAME(cc.id)
from CHECK_CARD cc
inner join CHECK_CARD chc
on cc.group_company_attr = chc.group_company_attr and cc.anc_report_date <= chc.anc_report_date and
chc.id = 1832307
where cc.status = 1
group by cc.id
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query = N'SELECT AttrName,' + #cols + N' from
(
select id, AttrName, value
from CHECK_CARD
cross apply
(
select ''RiskSignal'', cast(RiskSignalas varchar(50)) union all
select ''group_company_attr'', cast(group_company_attr varchar(50))
) c(AttrName, value)
) d
pivot
(
max(value)
for id in (' + #cols + N')
) piv';
exec sp_executesql #query;