Combining multiple rows in TSQL by case number - sql

Question

I'm new to SQL (more precisely T-SQL) and I can't seem to wrap my head around this one. I'm sure there is a simple solution and I'm just not thinking of (maybe involving subqueries and/or a table pivot). But I was hoping one of you SQL whizzes could help out a clueless newb.
Basically, I need to turn this data:
CaseNumber|DecisionNumber|Date |Decision
----------+--------------+-----------+--------
444 |29833 |04/05/2005 |Sell
444 |29777 |05/10/2006 |Sell
444 |29654 |08/19/2007 |Buy
468 |29230 |08/19/2006 |Sell
468 |29192 |08/19/2011 |Sell
Into this result:
CaseNumber|DecisionNumber1|Date1 |Decision1|DecisionNumber2|Date2 |Decision2|DecisionNumber3|Date3 |Decision3
----------+---------------+------------+---------+---------------+------------+---------+---------------+------------+---------
444 |29833 |04/05/2005 |Sell |29777 |05/10/2006 |Sell |29654 |08/19/2007 |Buy
468 |29230 |08/19/2006 |Sell |29192 |08/19/2011 |Sell |NULL |NULL |NULL
Any ideas would be MUCH appreciated.

Answer 1

The problem with what you are trying to do, is that you are trying to pivot more than one column at a time. This can be done with unpivot then pivot. Something like this:
WITH CTE
AS
(
SELECT
CAST(CaseNumber AS NVARCHAR(50)) AS CaseNumber
,CAST(DecisionNumber AS NVARCHAR(50)) AS DecisionNumber
,CAST(Date AS NVARCHAR(50)) AS [Date]
,ROW_NUMBER() OVER(PARTITION BY [CaseNumber] ORDER BY DecisionNumber DESC) AS RN
FROM Table1
), unpivoted
AS
(
SELECT CaseNumber, val, col + ' ' + CAST(RN AS NVARCHAR(50)) AS col
FROM CTE
UNPIVOT
(
val
FOR col IN(DecisionNumber, Date)
) AS u
)
SELECT *
FROM unpivoted AS u
PIVOT
(
MAX(val)
FOR col IN([DecisionNumber 1], [Date 1],
[DecisionNumber 2], [Date 2],
[DecisionNumber 3], [Date 3])
) AS p;
SQL Fiddle Demo
This will give you:
| CaseNumber | DecisionNumber 1 | Date 1 | DecisionNumber 2 | Date 2 | DecisionNumber 3 | Date 3 |
|------------|------------------|------------|------------------|------------|------------------|------------|
| 444 | 29833 | 2005-04-05 | 29777 | 2006-05-10 | 29654 | 2007-08-19 |
| 468 | 29230 | 2006-08-19 | 29192 | 2011-08-19 | (null) | (null) |
However, if you want to do this for any number of decisionnumber and date, you can do this:
DECLARE #cols AS NVARCHAR(MAX);
DECLARE #query AS NVARCHAR(MAX);
WITH CTE
AS
(
SELECT
CAST(CaseNumber AS NVARCHAR(50)) AS CaseNumber
,CAST(DecisionNumber AS NVARCHAR(50)) AS DecisionNumber
,CAST(Date AS NVARCHAR(50)) AS [Date]
,ROW_NUMBER() OVER(PARTITION BY [CaseNumber] ORDER BY DecisionNumber DESC) AS RN
FROM Table1
), Data
AS
(
SELECT col, MAX(RN) AS RN
FROM
(
SELECT RN, col + CAST(RN AS NVARCHAR(50)) AS col
FROM CTE
UNPIVOT
(
val
FOR col IN(DecisionNumber, Date)
) AS u
) AS t
GROUP BY col
)
select #cols = STUFF((SELECT ',' +
QUOTENAME(col)
FROM Data
ORDER BY RN
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
, 1, 1, '');
SELECT #query = 'WITH CTE
AS
(
SELECT
CAST(CaseNumber AS NVARCHAR(50)) AS CaseNumber
,CAST(DecisionNumber AS NVARCHAR(50)) AS DecisionNumber
,CAST(Date AS NVARCHAR(50)) AS [Date]
,ROW_NUMBER() OVER(PARTITION BY [CaseNumber] ORDER BY DecisionNumber DESC) AS RN
FROM Table1
), unpivoted
AS
(
SELECT CaseNumber, val, col + CAST(RN AS NVARCHAR(50)) AS col
FROM CTE
UNPIVOT
(
val
FOR col IN(DecisionNumber, Date)
) AS u
)
SELECT *
FROM unpivoted AS u
PIVOT
(
MAX(val)
FOR col IN('+ #cols + ')
) AS p;';
EXECUTE(#query);
Dynamic SQL Demo