Question

I’ve never used a SQL Pivot, but I think now’s my chance. Problem is, I really don’t know how. I’ve been reading documentation, but it seems like the result I want could be slightly complicated, and I can barely handle simple pivots at this point.

I have this table

Create table dataTable (dataID int, containerID int)

and I want to query it so that my result set is in the format:

Create table pivotTable (DataID int, Container1 bit, Container2 bit, ...ContainerN bit)

Where every DataID from dataTable becomes a row, and the bit-value for ConatinerN is 1 if the tuple {DataID, ContainerN} exists in dataTable, and 0 if it does not. There are 480 ContainerIDs, so I would rather not specify them all by hand, but I can if it’s necessary.

Thanks for the help!

Answer 1

Maybe something like this:

Test data

Create table dataTable (dataID int, containerID int)

INSERT INTO dataTable
VALUES
    (1,1),
    (2,1),
    (3,3),
    (4,2)

Unique columns

DECLARE @cols VARCHAR(MAX)
DECLARE @colsWithIsNull VARCHAR(MAX)
;WITH CTE
AS
(
    SELECT
        ROW_NUMBER() OVER(PARTITION BY containerID ORDER BY containerID) AS RowNbr,
        CAST(containerID AS VARCHAR(100)) AS containerID
    FROM 
        dataTable
)
SELECT  @cols = COALESCE(@cols + ','+QUOTENAME('Container'+containerID),
                    QUOTENAME('Container'+containerID)),
        @colsWithIsNull= COALESCE(@colsWithIsNull + ',CAST(ISNULL('+QUOTENAME('Container'+containerID)+',0) AS BIT) AS '+QUOTENAME('Container'+containerID),
                    'CAST(ISNULL('+QUOTENAME('Container'+containerID)+',0) AS BIT) AS '+QUOTENAME('Container'+containerID))
FROM
    CTE
WHERE
    CTE.RowNbr=1

Dynamic pivot

DECLARE @query NVARCHAR(4000)=
N'SELECT
    dataID,
    '+@colsWithIsNull+'
FROM
(
    SELECT
        ''Container''+CAST(dataTable.containerID AS VARCHAR(100)) AS ContainerText,
        1 AS isContainer,
        dataTable.dataID
    FROM
        dataTable
) AS p
PIVOT
(
    MAX(isContainer)
    FOR ContainerText IN ('+@cols+')
) AS pvt'

EXECUTE(@query)

In my case I will drop the test table:

DROP TABLE dataTable