SQL Using PIVOT for multi valued attributes - sql-server

Question

I designed an EAV table that looks like this:
SID AID VID
1 1 1
1 2 1
1 3 2
1 4 3
1 1 2
SID stand for Subject ID, AID stands for Attribute ID and VID stands for ValuedID
also a table to map the attributes:
AttributeID AttributeName
1 Hobbies
2 Name
3 Gender
4 IrisColor
After using pivot on the first table, linked to the attribute table:
SELECT
SubjectID,
Hobbies,
Name,
Gender,
IrisColor
FROM
(
SELECT SubjectID, attr.AttributeName as attribute, ValueID from SubjectDetails, SubjectAttributes as attr WHERE SubjectDetails.AttributeID=attr.ID
) as t
PIVOT(
MAX(ValueID)
FOR attribute IN (Hobbies,Name,Gender,IrisColor)) AS t1
WHERE SubjectID=1
I get this:
SubjectID Hobbies Name Gender IrisColor
1 1 1 2 3
Which is almost correct, but SubjectAttribute 1 (which is hobbies) appears one more time in the first table (SubjectDetails), so what I want to achieve is this:
SubjectID Hobbies Name Gender IrisColor
1 **1,2** 1 2 3
I have to mention that I don't care about what separator is used and that I tried doing that with the STUFF function but it is a pain to combine PIVOT and STUFF (or I just don't know how).. Any suggestions?

Answer 1

This should work, I did the following:
Stored the information from your EAV table (table1) as single row per SID into a temporary table (you can create a view instead).
Then pivoted that resultset as below (using your pivot query):
SELECT *
FROM
(
SELECT * from #temptbl
) as t
PIVOT( MAX(vid) FOR attrname IN (Hobbies,Name,Gender,IrisColor)) AS t1
WHERE sid=1
I got this result:
Please check the full working version here.

Answer 2

This would work without using PIVOT, I think here no need to use PIVOT
SELECT SubjectID
,+STUFF((SELECT ', '+CAST(ValueID AS NVARCHAR)
FROM #T_SubjectAttributes A
INNER JOIN #T_SubjectDetails B ON A.AttributeID = B.AttributeId
WHERE AttributeName = 'Hobbies'
AND B.SubjectID = H.SubjectID FOR XML PATH(''))
,1,2,'') AS Hobbies
,STUFF((SELECT ', '+CAST(ValueID AS NVARCHAR)
FROM #T_SubjectAttributes A
INNER JOIN #T_SubjectDetails B ON A.AttributeID = B.AttributeId
WHERE AttributeName = 'Name'
AND B.SubjectID = H.SubjectID FOR XML PATH(''))
,1,2,'') AS Name
,STUFF((SELECT ', '+CAST(ValueID AS NVARCHAR)
FROM #T_SubjectAttributes A
INNER JOIN #T_SubjectDetails B ON A.AttributeID = B.AttributeId
WHERE AttributeName = 'Gender'
AND B.SubjectID = H.SubjectID FOR XML PATH(''))
,1,2,'') AS Gender
,STUFF((SELECT ', '+CAST(ValueID AS NVARCHAR)
FROM #T_SubjectAttributes A
INNER JOIN #T_SubjectDetails B ON A.AttributeID = B.AttributeId
WHERE AttributeName = 'IrisColor'
AND B.SubjectID = H.SubjectID FOR XML PATH(''))
,1,2,'') AS IrisColor
FROM #T_SubjectDetails H
GROUP BY SubjectID