Join with dynamic pivot - sql

Question

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Join with dynamic pivot (version 2)
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The query should automaticly work if a new position record is added. Thanks you

Answer 1

SELECT
c.CategoryId AS CID,
c.CategoryName,
ISNULL(t.CategoryOrder, 0) AS [Top],
ISNULL(l.CategoryOrder, 0) AS [Left],
ISNULL(r.CategoryOrder, 0) AS [Right]
FROM
Category c
LEFT JOIN CategoryPosition t ON t.CategoryId = c.CategoryId
AND t.PositionId = 1
LEFT JOIN CategoryPosition l ON l.CategoryId = c.CategoryId
AND l.PositionId = 2
LEFT JOIN CategoryPosition r ON r.CategoryId = c.CategoryId
AND r.PositionId = 3

Answer 2

Messy, but it works
select c.categoryid,c.categoryname
,COALESCE((select top 1 categoryorder from categoryposition where categoryid=c.categoryid and positionid=1),0) as [top]
,COALESCE((select top 1 categoryorder from categoryposition where categoryid=c.categoryid and positionid=2),0) as [left]
,COALESCE((select top 1 categoryorder from categoryposition where categoryid=c.categoryid and positionid=3),0) as [right]
from categoryposition cp,category c
where cp.categoryid=c.categoryid
group by c.categoryid,c.categoryname
order by 1
Two things to keep in mind. If you can ensure that there is at most one position for each categoryposition then you can remove the top 1, but the subquery must return 1 row o nothing for it to work.

Answer 3

Since you want the cross tab query to be dynamic based on the contents of Position table then I recommend that you dynamicly generate the SQL at runtime.
-- Start with Query frame
DECLARE #Query NVARCHAR(4000)
SET #Query = '
Select
Category.CategoryID,
Category.CategoryName
<DYNAMICQUERY>
From CategoryPosition
Inner Join Category ON Category.CategoryID = CategoryPosition.CategoryID
Group By Category.CategoryID, Category.CategoryName';
SELECT #Query;
-- Build the dynamic part of query
DECLARE #DynamicQuery VARCHAR(1024)
DECLARE #PositionCol VARCHAR(256)
DECLARE dynamic_sql CURSOR FOR
SELECT ',MAX(CASE WHEN CategoryPosition.PositionID = '+CAST(PositionID AS varchar(10)) +' THEN CategoryPosition.CategoryOrder ELSE 0 END) AS ['+PositionName+']'
From Position
OPEN dynamic_sql
FETCH NEXT FROM dynamic_sql
INTO #PositionCol
SELECT #DynamicQuery = #PositionCol;
WHILE ##FETCH_STATUS = 0
BEGIN
FETCH NEXT FROM dynamic_sql
INTO #PositionCol
SELECT #DynamicQuery = #DynamicQuery+#PositionCol;
END
CLOSE dynamic_sql
DEALLOCATE dynamic_sql
SELECT #Query = REPLACE(#Query, '<DYNAMICQUERY>', #DynamicQuery)
-- Execute the Query
EXECUTE sp_executesql #Query