Rotate table in T-SQL - sql

Question

I have a table that contains sequential date in first column and type of date (CreatedOn and ClosedOn). I need to with SELECT that has 2 columns (CreatedOn, ClosedOn) from my table.
I have this:
| Date | ColumnName |
|------------|------------|
| 2017-01-01 | ClosedOn |
| 2017-01-02 | CreatedOn |
| 2017-01-03 | ClosedOn |
| 2017-01-04 | CreatedOn |
And I need to get this:
| CreatedOn | ClosedOn |
|------------|------------|
| NULL | 2017-01-01 |
| 2017-01-02 | 2017-01-03 |
| 2017-01-04 | NULL |
I've tried this:
SELECT
CASE [ColumnName]
WHEN 'CreatedOn' THEN [Date]
ELSE NULL
END,
CASE [ColumnName]
WHEN 'ClosedOn' THEN [Date]
ELSE NULL
END
FROM #Temp
but it doesn't work.

Answer 1

This is a typical case of using a PIVOT in SQL Server, to transpose rows into columns:
select *
from table1
pivot (max(colname) for colname in (ClosedOn, CreatedOn)) p
order by date

Answer 2

Try this and hope it helps. You may have to test it and modify as needed. But the logic if my understanding is correct should be sufficient to build on.
;WITH cte_TestData(Date,ColumnName) AS
(
SELECT '2017-01-01','ClosedOn ' UNION ALL
SELECT '2017-01-02','CreatedOn' UNION ALL
SELECT '2017-01-03','ClosedOn ' UNION ALL
SELECT '2017-01-04','CreatedOn'
)
,cte_PreserveSeq AS
(
SELECT ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS SeqID,Date,ColumnName
FROM cte_TestData
)
,cte_PreResult AS
(
SELECT *
,LEAD (ColumnName, 1,0) OVER (ORDER BY SeqID) AS NextColumnName
,LEAD (Date, 1,0) OVER (ORDER BY SeqID) AS NextDate
,LAG (ColumnName, 1,0) OVER (ORDER BY SeqID) AS PreviousColumnName
,LAG (Date, 1,0) OVER (ORDER BY SeqID) AS PreviousDate
FROM cte_PreserveSeq
)
SELECT DISTINCT
CASE
WHEN ColumnName = 'CreatedOn' AND NextColumnName = 'ClosedOn' THEN DATE
WHEN ColumnName = 'ClosedOn' AND PreviousColumnName = 'CreatedOn' THEN PreviousDate
WHEN ColumnName = 'CreatedOn' THEN DATE
ELSE NULL
END AS CreatedOn,
CASE
WHEN ColumnName = 'CreatedOn' AND NextColumnName = 'ClosedOn' THEN NextDate
WHEN ColumnName = 'ClosedOn' THEN DATE
ELSE NULL
END AS ClosedOn
FROM cte_PreResult

Answer 3

I'm assuming you have other columns, so let's do this
select A1.OtherColumn, A1.[Date], A2.Date
from #Temp A1
full outer join #Temp A2
on A1.OtherColumn = A2.OtherColumn
and A1.ColumnName = 'CreatedOn'
and A2.ColumnName = 'ClosedOn'
EDIT: If no other columns, try
with MyData as
(
select [Date], ColumnName , row_number() over (order by [Date], ColumnName desc) as rn
from #Temp
)
select M1.[Date], M2.[Date]
from MyData M1
full outer join MyData M2
on M2.rn = M1.rn + 1
and mod(M1.rn, 2) = 1