Random Order by in SQL Server - sql-server

Question

I got the data using this query:
SELECT PT.ID AS ProductTypeId,
PT.ProductType,
PTPS.ID AS AssetId,
PTPS.Ordinal AS AssetOrdinal,
CASE
WHEN PTPS.LinkType = 2
THEN
--DS.ServerRootURL + 'Videos/ProductTypes/' +
--PTPSMaterialImage.LinkURL
(
SELECT TOP 1 LinkURL
FROM ProductTypesPblmSolutions
WHERE ProductTypeId = PT.ID
AND LinkType = 1
ORDER BY ID DESC
)
ELSE PTPS.LinkURL
END AS MaterialImage,
ATL.LinkType
FROM ProductTypes PT
INNER JOIN ProductTypesToApps PTA ON PT.ID = PTA.ProductTypeId
INNER JOIN ProductTypesPblmSolutions PTPS ON PTPS.ProductTypeId = PT.ID
INNER JOIN DealerSettings DS ON DS.DealerId = 23
INNER JOIN AttachmentLinkTypes ATL ON ATL.ID = PTPS.LinkType
WHERE PTA.AppId = 3
AND (PT.ID = 202 OR 202 IS NULL)
AND (ISNULL(PTPS.IsDeleted, 0) = 0)
ORDER BY PTPS.Ordinal
Let's talk about the materialimage column. I have to get two different images for this producttype but for now I am getting the same product.
There are lot of linkurls exist for this product. Please refer this query below and its data.
SELECT ProductTypeId,
linkurl,
linktype
FROM ProductTypesPblmSolutions
WHERE ProductTypeId = 202
AND linktype = 1
The same thing I used it as subquery in my Main query
How do I get different images in this column.
I tried with TOP 1 ... ORDER BY NEWID() but it does NOT work.

Answer 1

Just to be clear, the subquery should look like:
(SELECT TOP 1 ptps2.LinkURL
FROM ProductTypesPblmSolutions ptps2
WHERE ptps2.ProductTypeId = PT.Id AND
ptps2.LinkType = 1
ORDER BY NEWID()
)
Note the use of qualified column names and the NEWID() in the ORDER BY.
I recommend always using qualified column names. This is especially true in correlated subqueries, where errors are easy to make and very difficult to find (although that might not be the problem in this particular case).
If you see no effect from this, then I would assume that the else component of the case is being executed, rather than the subquery.

Answer 2

SELECT TOP(1) t.LinkURL
FROM dbo.ProductTypesPblmSolutions t
WHERE t.ProductTypeId = PT.ID
AND t.LinkType = 1
ORDER BY NEWID(), PT.ID -- additional calculation
Example #1:
SELECT TOP(10) s.number, (
SELECT TOP(1) s1.number
FROM [master].dbo.spt_values s1
WHERE s1.[type] = s.[type]
ORDER BY NEWID()
)
FROM [master].dbo.spt_values s
WHERE s.[type] = 'P'
Output:
----------- -----------
0 844
1 844
2 844
3 844
4 844
5 844
6 844
7 844
8 844
9 844
Example #2:
SELECT TOP(10) s.number, (
SELECT TOP(1) s1.number
FROM [master].dbo.spt_values s1
WHERE s1.[type] = s.[type]
ORDER BY NEWID(), s.[type] -- <<<< additional calculation
)
FROM [master].dbo.spt_values s
WHERE s.[type] = 'P'
Output:
----------- -----------
0 428
1 801
2 550
3 1619
4 178
5 17
6 1702
7 683
8 352
9 1844