Stored Procedure: Pivot With Dynamic Columns

Following is a stored procedure in aims to improve Microsoft built-in function of PIVOT in SQL Server. To use PIVOT, one must know exact number and name of columns after pivot, which does not meet the real world’s need. What we need is the pivot function works with dynamic pivot columns. To use this stored procedure, you would need to create a temporary table first with name of “Temp_Transform_Input”. Following is the structure of the this table:

Column 1, can be any name and data type. It would remain intact as it was after pivot.
Column 2, must be named as “Pivot_Column” and should be VARCHAR data type. Its contents after automatically distinct would be pivoted as column titles after execute this procedure.
Column 3, must be named as “Content_Column” and should be INT data type. It would be summed up after pivot. If the purpose is to count, put 1 here for every record.

To use it, just type EXECUTE P_Transform GO. The result will be automatically saved into 7 temporary tables. You do not need to manage the garbage collection for these two temporary tables, this procedure will manage them for you.

Why use temporary table instead of use Multi-statement Table-Valued Function as output method? Since you are dealing with the dynamic columns, it is impossible to declare the return table in Multi-statement Table-Valued Function.

CREATE PROCEDURE P_Transform
AS
BEGIN
IF EXISTS( SELECT *
FROM SYS.TABLES
WHERE NAME = 'Temp_Transform_Row_Largest'
)
DROP TABLE dbo.Temp_Transform_Row_Largest
IF EXISTS( SELECT *
FROM SYS.TABLES
WHERE NAME = 'Temp_Transform_Row_Sum'
)
DROP TABLE dbo.Temp_Transform_Row_Sum
IF EXISTS( SELECT *
FROM SYS.TABLES
WHERE NAME = 'Temp_Transform_Column_Largest'
)
DROP TABLE dbo.Temp_Transform_Column_Largest
IF EXISTS( SELECT *
FROM SYS.TABLES
WHERE NAME = 'Temp_Transform_Column_Sum'
)
DROP TABLE dbo.Temp_Transform_Column_Sum
IF EXISTS( SELECT *
FROM SYS.TABLES
WHERE NAME = 'Temp_Transform_Both_Largest'
)
DROP TABLE dbo.Temp_Transform_Both_Largest
IF EXISTS( SELECT *
FROM SYS.TABLES
WHERE NAME = 'Temp_Transform_Both_Sum'
)
DROP TABLE dbo.Temp_Transform_Both_Sum
IF EXISTS( SELECT *
FROM SYS.TABLES
WHERE NAME = 'Temp_Transform_Result'
)
DROP TABLE dbo.Temp_Transform_Result
DECLARE @FirstColumn VARCHAR(128)
DECLARE @Summary VARCHAR(512)
DECLARE @Columns VARCHAR(MAX)
DECLARE @Query VARCHAR(MAX)
SELECT @FirstColumn = COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'Temp_Transform_Input'
AND ORDINAL_POSITION = 1
SET @Summary =
'
SELECT ' + @FirstColumn + '
, MAX(Content_Column) AS Largest
INTO Temp_Transform_Row_Largest
FROM Temp_Transform_Input
GROUP BY ' + @FirstColumn + '
ORDER BY MAX(Content_Column) DESC
, ' + @FirstColumn + '
'
EXECUTE(@Summary)
SET @Summary =
'
SELECT ' + @FirstColumn + '
, SUM(Content_Column) AS Total
INTO Temp_Transform_Row_Sum
FROM Temp_Transform_Input
GROUP BY ' + @FirstColumn + '
ORDER BY SUM(Content_Column) DESC
, ' + @FirstColumn + '
'
EXECUTE(@Summary)
SET @Summary =
'
SELECT Pivot_Column
, MAX(Content_Column) AS Largest
INTO Temp_Transform_Column_Largest
FROM Temp_Transform_Input
GROUP BY Pivot_Column
ORDER BY MAX(Content_Column) DESC
, Pivot_Column
'
EXECUTE(@Summary)
SET @Summary =
'
SELECT Pivot_Column
, SUM(Content_Column) AS Total
INTO Temp_Transform_Column_Sum
FROM Temp_Transform_Input
GROUP BY Pivot_Column
ORDER BY SUM(Content_Column) DESC
, Pivot_Column
'
EXECUTE(@Summary)
SET @Summary =
'
SELECT ' + @FirstColumn + '
, Pivot_Column
, MAX(Content_Column) AS Largest
INTO Temp_Transform_Both_Largest
FROM Temp_Transform_Input
GROUP BY ' + @FirstColumn + '
, Pivot_Column
ORDER BY MAX(Content_Column) DESC
, Pivot_Column
'
EXECUTE(@Summary)
SET @Summary =
'
SELECT ' + @FirstColumn + '
, Pivot_Column
, SUM(Content_Column) AS Total
INTO Temp_Transform_Both_Sum
FROM Temp_Transform_Input
GROUP BY ' + @FirstColumn + '
, Pivot_Column
ORDER BY SUM(Content_Column) DESC
, ' + @FirstColumn + '
, Pivot_Column
'
EXECUTE(@Summary)
SELECT @Columns = COALESCE( @Columns + ',[' + CAST(LTRIM(RTRIM(Pivot_Column)) AS VARCHAR) + ']'
, '[' + CAST(LTRIM(RTRIM(Pivot_Column)) AS VARCHAR)+ ']'
)
FROM
(
SELECT DISTINCT Pivot_Column
FROM Temp_Transform_Input
) AS Base_Q
SET @Query =
'
SELECT *
INTO Temp_Transform_Result
FROM
(
SELECT *
FROM Temp_Transform_Input
) AS Inner_Q
PIVOT
(
SUM(Content_Column)
FOR Pivot_Column IN (' + @Columns + ')
) AS Pivot_Q
'
EXECUTE(@Query)
IF EXISTS( SELECT *
FROM SYS.TABLES
WHERE NAME = 'Temp_Transform_Input'
)
DROP TABLE dbo.Temp_Transform_Input
END
GO

It is very important the length of each contents in Pivot_Column must be less 30 characters, because the contents will become the column name after transpose. Else, it won't work properly.


http://www.paladn.com/component/content/article/40-sql-server/122-udf-forms.html