No Results returned for ROW_NUMBER() query

Question

I am getting "no results returned" for the following query:

SELECT 
    Referer 
FROM 
    (SELECT 
        ROW_NUMBER() OVER (ORDER BY CT.Referer ASC) AS RowNum, 
        CT.Referer, CT.LastModified
     FROM 
        ClickTrack CT 
     JOIN 
        OrderTrack OT ON OT.ClickTrackID = CT.ClickTrackID              
     GROUP BY 
        CT.Referer, CT.LastModified
     HAVING 
        LEN(CT.Referer) > 0) as num 
WHERE 
    RowNum = 1 
    AND LastModified BETWEEN '07/06/2013' and '08/05/2013'

Curiously, when I leave off RowNum = 1, I get the full list of values. I need to get one at a time though to assign to a variable and drop into a temporary table.

The end query will be in a while loop using scalar variables in place of the date ranges and RowNum comparison.

Any help is appreciated. Thank you!

Answer 1

I'm thinking RowNum 1 may not have a date between your selections. Maybe put the date selection inside so that you know that the first one matches.

    SELECT Referer 
    FROM (SELECT ROW_NUMBER() OVER (ORDER BY CT.Referer ASC) 
    AS RowNum, CT.Referer, CT.LastModified
    FROM ClickTrack CT 
    JOIN OrderTrack OT ON OT.ClickTrackID = CT.ClickTrackID    
    WHERE CT.LastModified BETWEEN '07/06/2013' and '08/05/2013'          
    GROUP BY CT.Referer, CT.LastModified
    HAVING LEN(CT.Referer) > 0) as num 
    WHERE RowNum = 1