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SELECT DISTINCT w/Join, ORDER BY in CASE

Hello Experts,

Using MS SQL Server 2005...

Hopefully this is easy to solve. I have a stored procedure that I use as a datasource for a drop down list. This drop down list could contain a couple hundred items, so I provide the user with the ability to filter and sort the drop down list to help them find what they want to select. So I have one optional parameter that filters the list, and another that changes the sort order. Problem is, this query uses a join (1 to many), and my list comes up with duplicates. No problem, just apply the DISTINCT predicate. As soon as I do that, SQL Server complains that "ORDER BY items must appear in the select list if SELECT DISTINCT is specified". I don't know what I need to specify in the select list because I'm using a case statement to order dynamically based on an input parameter.

Here is my stored procedure. Please advise!

ALTER PROCEDURE [dbo].[jwSiteMetaData]
	@SiteID as int = null,
	@SiteType as varchar(50) = null,
	@SortOrder as varchar(20) = 'SD.SiteID'
AS
BEGIN
	SET NOCOUNT ON;

	IF @SiteType = '' SET @SiteType = null
	IF @SortOrder = 'SiteID' SET @SortOrder = 'SD.SiteID'

	SELECT DISTINCT convert(varchar,SD.SiteID) + ' - ' + SiteName AS SiteIDSiteName, SD.SiteID, SiteName 
	FROM SiteDef AS SD LEFT JOIN SiteTypes AS ST ON SD.SiteID=ST.SiteID
	WHERE SD.SiteID = coalesce(@SiteID,SD.SiteID)
		AND ST.SiteType = coalesce(@SiteType, ST.SiteType)
	ORDER BY
		CASE
			WHEN @SortOrder = 'SiteName' THEN (RANK() OVER (ORDER BY SiteName))
			ELSE (RANK() OVER (ORDER BY SD.SiteID))
		END
END

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Guy Hengel [angelIII / a3]

you migth want to read this article:
https://www.experts-exchange.com/A_3203.html

1 possibility might be this:

ALTER PROCEDURE [dbo].[jwSiteMetaData]
        @SiteID as int = null,
        @SiteType as varchar(50) = null,
        @SortOrder as varchar(20) = 'SD.SiteID'
AS
BEGIN
        SET NOCOUNT ON;

        IF @SiteType = '' SET @SiteType = null
        IF @SortOrder = 'SiteID' SET @SortOrder = 'SD.SiteID'

        SELECT SiteIDSiteName, SiteID, SiteName
          FROM ( 
           SELECT convert(varchar,SD.SiteID) + ' - ' + SiteName AS SiteIDSiteName
            , SD.SiteID, SiteName 
            , CASE 
              WHEN @SortOrder = 'SiteName' THEN (RANK() OVER (ORDER BY SiteName))
              ELSE (RANK() OVER (ORDER BY SD.SiteID))
               END rn
            FROM SiteDef AS SD 
            LEFT JOIN SiteTypes AS ST 
              ON SD.SiteID=ST.SiteID
           WHERE SD.SiteID = coalesce(@SiteID,SD.SiteID)
             AND ST.SiteType = coalesce(@SiteType, ST.SiteType)
        ) sq
        GROUP BY SiteIDSiteName, SiteID, SiteName
        ORDER BY MAX(rn)
                
END

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HainKurt

do this

if @SortOrder="..."
begin
select ...
end

if @SortOrder="..."
begin
select ...
end

use different simple statements instead of trying to order by complicated statements...

Racim BOUDJAKDJI

Do what HainKurt suggested. Better both for readability and performance. (pls no poinks)

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Valliappan AN

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Jahelka

ASKER

I hadn't thought to use a Group By as I usually only use those in conjunction with max() or min() or one of those guys. Nice, elegant solution!

HainKurt, wouldn't your solution be considered "dynamic sql" and mean that a query plan would have to be rebuilt each time the stored proc was run? I can understand that sometimes readability and maintanance considerations can outweigh the performance considerations, but don't you want to try to avoid dynamic sql if at all possible?

Thanks for your very prompt and helpful responses guys.

Racim BOUDJAKDJI

What Hainkurt suggest is not dynamic SQL. dynamic SQL works by variabilizing strings which is different, and f course should be avoided for security reasons...

Jahelka

ASKER

Ahh, OK. I see the difference now that I look closer. Each SQL statement would be complete on its own, you are just changing which one you execute based on the input parameter. Apologies for the ignorance. Thanks for the help.