Wednesday 31 May 2017

sql server - T-SQL dynamic pivot



Ok I have a table that looks like this



ItemID | ColumnName | Value
1 | name | Peter
1 | phone | 12345678
1 | email | peter@host.com

2 | name | John
2 | phone | 87654321
2 | email | john@host.com
3 | name | Sarah
3 | phone | 55667788
3 | email | sarah@host.com


Now I need to turn that into this:




ItemID | name  | phone    | email
1 | Peter | 12345678 | peter@host.com
2 | John | 87654321 | john@host.com
3 | Sarah | 55667788 | sarah@host.com


I have been looking at dynamic pivot examples, but it seems Im not able to fit them into my scenario.



Can anyone help?


Answer




Have a look at the following example



CREATE TABLE #Table (
ID INT,
ColumnName VARCHAR(250),
Value VARCHAR(250)
)

INSERT INTO #Table SELECT 1,'name','Peter'
INSERT INTO #Table SELECT 1,'phone','12345678'

INSERT INTO #Table SELECT 1,'email','peter@host.com'
INSERT INTO #Table SELECT 2,'name','John'
INSERT INTO #Table SELECT 2,'phone','87654321'
INSERT INTO #Table SELECT 2,'email','john@host.com'
INSERT INTO #Table SELECT 3,'name','Sarah'
INSERT INTO #Table SELECT 3,'phone','55667788'
INSERT INTO #Table SELECT 3,'email','sarah@host.com'

---I assumed your tablename as TESTTABLE---
DECLARE @cols NVARCHAR(2000)

DECLARE @query NVARCHAR(4000)

SELECT @cols = STUFF(( SELECT DISTINCT TOP 100 PERCENT
'],[' + t.ColumnName
FROM #Table AS t
--ORDER BY '],[' + t.ID
FOR XML PATH('')
), 1, 2, '') + ']'

SELECT @cols


SET @query = N'SELECT ID,'+ @cols +' FROM
(SELECT t1.ID,t1.ColumnName , t1.Value FROM #Table AS t1) p
PIVOT (MAX([Value]) FOR ColumnName IN ( '+ @cols +' ))
AS pvt;'

EXECUTE(@query)

DROP TABLE #Table


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