Question

I have following SQL query but this is not quite what I want:

SELECT 
    TOP (20) Attribs.ImageID AS ItemID 
FROM 
    Attribs 
LEFT OUTER JOIN 
    Items ON Attribs.ImageID = Items.ImageID 
WHERE
    (attribID IN ('a','b','c','d','e')) 
    AND (deleted NOT IN (1,2)) 
    AND Attribs.attribID = 'a' AND Attribs.attribID = 'b'
GROUP BY 
    Attribs.ImageID 
ORDER BY 
    COUNT(DISTINCT attribID) DESC

What I need is to query

   AND Attribs.attribID = 'a' AND Attribs.attribID = 'b'

first, then rest of the WHERE clause based on the above query results.

Is this possible to achieve using sub query?

I’m using SQL Server 2008

Thank you

Answer 1

I’m not totally getting the reason why you want to do this one query first before the other…. but you could use a Common Table Expression (CTE) – something like this:

;WITH FirstQuery AS
(
    SELECT a.ImageId
    FROM dbo.Attribs a
    WHERE a.attribID = 'a' AND a.attribID = 'b'
)
SELECT 
    TOP (20) a.ImageID AS ItemID 
FROM 
    dbo.Attribs a
INNER JOIN
    FirstQuery fq ON a.ImageId = fq.ImageId  
LEFT OUTER JOIN 
    dbo.Items i ON a.ImageID = i.ImageID 
WHERE
    (attribID IN ('a','b','c','d','e')) 
    AND (deleted NOT IN (1,2)) 
GROUP BY 
    a.ImageID 
ORDER BY 
    COUNT(DISTINCT attribID) DESC

With this, you first select the ImageID from your dbo.Attribs table in the CTE, and then join that result set with the result of the table and join to the Items table.