CODEWITHSUNDEEP
t-sqlpaginationdynamic-sqlcommon-table-expression
Rob
Rob

Reputation: 10248

T-SQL dynamic Order By in Common Table for pagination

I found some great sql code for dynamic sort & order but I am wondering if someone can help me re-jig it so that the CTE in the PROC below uses the dynamic sort/order. This code runs - but the output is not what I am after as the ORDER BY p.ProductId happens first in the CTE then the ORDER BY CASE statement only applies to the records 6 to 10

DECLARE @Skip int
DECLARE @Take int
DECLARE @OrderBy VARCHAR(50)

SET @Skip = 5;
SET @Take = 5;
SET @OrderBy = 'PriceAsc';


WITH ProductCT AS
(
    SELECT ROW_NUMBER() OVER(ORDER BY p.ProductId) AS RowNum
    , p.ProductId
    FROM dbo.Product AS p
)
SELECT   p.ProductId
        ,p.Title
        ,p.Price
FROM dbo.Product AS p
INNER JOIN ProductCT AS pct ON pct.ProductId = p.ProductId
WHERE pct.RowNum BETWEEN @Skip + 1 AND (@Skip + @Take)
ORDER BY
    CASE     
         WHEN @OrderBy = 'TitleAsc' THEN (RANK() OVER (ORDER BY p.Title))
         WHEN @OrderBy = 'TitleDesc' THEN (RANK() OVER (ORDER BY p.Title DESC))
         WHEN @OrderBy = 'PriceAsc' THEN (RANK() OVER (ORDER BY p.Price))
         WHEN @OrderBy = 'PriceDesc' THEN (RANK() OVER (ORDER BY p.Price DESC))
         ELSE (RANK() OVER (ORDER BY p.Price))
    END

Thanks in advance for any suggestions :-)

Upvotes: 4

Views: 3884

Answers (3)

Vincent
Vincent

Reputation: 762

Rob's solutions somehow doesn't work for me, here is my modified version which worked fine. 

       SELECT
          ROW_NUMBER() OVER (ORDER BY 
    CASE
       WHEN @sortOrder = 'TitleAsc' THEN p.Title
       WHEN @sortOrder = 'TitleDesc' THEN  p.Title
       WHEN @sortOrder = 'PatientId' THEN  p.Title
       WHEN @sortOrder = 'PriceAsc' THEN  p.Title
       WHEN @sortOrder = 'PriceDesc' THEN  p.Title
    END ASC) AS [RowNum],
       .................
      ..................

Upvotes: 0

Rob
Rob

Reputation: 10248

I originally marked the answer from @Johan as correct because it worked, but I was a little unsure about the INNER JOIN also the overall complexity of this query.

I got chatting with a colleague of mine about the problem and he came up with this very tidy solution (thanks Tom!!) so I thought I would share it:

DECLARE @Skip int
DECLARE @Take int
DECLARE @OrderBy VARCHAR(50)

SET @Skip = 5;
SET @Take = 5;
SET @OrderBy = 'PriceAsc';


WITH ProductCT AS
(
    SELECT
    CASE
       WHEN @OrderBy = 'TitleAsc' THEN ROW_NUMBER() OVER (ORDER BY p.Title)
       WHEN @OrderBy = 'TitleDesc' THEN ROW_NUMBER() OVER (ORDER BY p.Title DESC)
       WHEN @OrderBy = 'PriceAsc' THEN ROW_NUMBER() OVER (ORDER BY p.Price)
       WHEN @OrderBy = 'PriceDesc' THEN ROW_NUMBER() OVER (ORDER BY p.Price DESC)
    END AS RowNum
    , p.ProductId
    FROM dbo.Product AS p
)
SELECT   p.ProductId
        ,p.Title
        ,p.Price
FROM dbo.Product AS p
INNER JOIN ProductCT AS pct ON pct.ProductId = p.ProductId
WHERE pct.RowNum BETWEEN @Skip + 1 AND (@Skip + @Take)
ORDER BY RowNum

Upvotes: 10

Johan
Johan

Reputation: 1192

Here is a solution that should work.

WITH ProductCT AS
(
    SELECT  ROW_NUMBER() OVER(ORDER BY p.Title) AS RowNum1
            ,ROW_NUMBER() OVER(ORDER BY p.Title DESC) AS RowNum2
            ,ROW_NUMBER() OVER(ORDER BY p.Price) AS RowNum3
            ,ROW_NUMBER() OVER(ORDER BY p.Price DESC) AS RowNum4
            ,p.ProductId
    FROM dbo.Product AS p
)
SELECT   p.ProductId
        ,p.Title
        ,p.Price
FROM dbo.Product AS p
INNER JOIN ProductCT AS pct 
    ON  pct.ProductId = p.ProductId
    AND ((@OrderBy = 'TitleAsc' AND pct.RowNum1 BETWEEN @Skip + 1 AND (@Skip + @Take))
    OR  (@OrderBy = 'TitleDesc' AND pct.RowNum2 BETWEEN @Skip + 1 AND (@Skip + @Take))
    OR  (@OrderBy = 'PriceAsc' AND pct.RowNum3 BETWEEN @Skip + 1 AND (@Skip + @Take))
    OR  (@OrderBy = 'PriceDesc' AND pct.RowNum4 BETWEEN @Skip + 1 AND (@Skip + @Take))
    )
ORDER BY
    CASE @OrderBy
         WHEN 'TitleAsc' THEN RowNum1
         WHEN 'TitleDesc' THEN RowNum2
         WHEN 'PriceAsc' THEN RowNum3
         WHEN 'PriceDesc' THEN RowNum4
         ELSE RowNum3
    END

I think the JOIN could be written better but I dont have more time right now.

Upvotes: 0

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