Question

I am having a bit of a brain block with this problem and I am finding it hard to search for a solution because I cant phrase the question correctly to bring up the relevant information.

I am trying to get back “fProduct” record from the table below where it has a “fAttribute”
of 2 and 20.

id  fAttribute  fProduct
19      2        2967
48      2        2923
50      2        3008
51      20       3008
52      2        2295
53      20       2295

My statment below produces 0 results when I would expect to return fProduct’s 2295 and 3008.

SELECT fProduct 
FROM  tableName 
WHERE fAttribute = 2 AND fAttribute = 20
GROUP BY fProduct

Can anyone help please?

Answer 1

You can either use INNER JOINS or use EXISTS conditions:

INNER JOIN:

SELECT DISTINCT a.fProduct
FROM MyTable a
     INNER JOIN MyTable b ON a.fProduct = b.fProduct AND b.fAttribute = 2
     INNER JOIN MyTable c ON a.fProduct = c.fProduct AND c.fAttribute = 20

EXISTS:

SELECT afproduct
FROM MyTable a
WHERE EXISTS (SELECT b.id FROM MyTable b WHERE a.fProduct = b.fProduct AND b.fAttribute = 2)
  AND EXISTS (SELECT c.id FROM MyTable c WHERE a.fProduct = c.fProduct AND c.fAttribute = 20)