Question

I have 2 tables, a product table and an image table. Products can have more than 1 image per record. I need an SQL statement that will list 1 image per product rather than all images per product.

A scaled down example of my current effort is:

SELECT Product.RefCode, Img.ImgPath
FROM Product INNER JOIN (
    SELECT ProductImg.ImgPath, ProductImg.PrdFK
    FROM ProductImg 
    LIMIT 0,1) AS Img ON Product.PrdID = Img.PrdFK;

The above example returns 0 results, however, if I remove the LIMIT 0,1 from the Sub SELECT I get a complete list of all products and all images.

I just want 1 image record per product record to be returned.

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I have revised “a programmer” code to MySQL and it works fine.

SELECT Product.RefCode, 
        (Select ProductImg.ImgPath
         From ProductImg
         Where Product.PrdID = Img.PrdFK LIMIT 0,1) AS ImgPath
FROM Products

For some reason when trying “Bill Karwin’s” solution, it sent the server loading for a long time.

Answer 1

This should work:

SELECT Product.RefCode,
       (Select Img.ImgPath
        From ProductImg
        Where Product.PrdID = Img.PrdFK LIMIT 0,1) As ImgPath
FROM Product

If you have a way to determine which image should the select return, then you can add a where and maybe an Order By in the sub-select.

In the following example, we’ll get only the latest of the active images.

SELECT Product.RefCode,
       (Select Img.ImgPath
        From ProductImg
        Where Product.PrdID = Img.PrdFK
          And IsActive = 1
        Order By EntryDate Desc LIMIT 0,1) As ImgPath
FROM Product

Edited and corrected ‘Top 1’ to ‘Limit 0,1’.