SELECT Statement using INTERSECT - sql

Question

I have two tables: tblProduct which has list of Products, and tblConsumer which has consumer name with consumed product ID.
Now I need to find the name of consumers who have consumed all products from the product table.
I tried to solve this with using INTERSECT, but the problem is I have provide each productid in WHERE clause. This syntax gives the result that I wanted, but how do I write this query where I don’t need to specify each productID.
SELECT ConsumerName FROM tblConsumer WHERE ProductID= 1
INTERSECT
SELECT ConsumerName FROM tblConsumer WHERE ProductID =2
INTERSECT
SELECT ConsumerName FROM tblConsumer WHERE ProductID =3
tblProduct
---------------------------------
ProductID | Product Name
---------------------------------
1 | Mango
2 | Orange
3 | Banana
tblConsumer
---------------------------------
ConsumerName | ProductID
---------------------------------
David | 1
David | 3
David | 2
Henry | 3
Henry | 2

Answer 1

If you're actually wanting to list all the Products in tblProducts, then you can use NOT EXISTS...
Otherwise, if you have a list of the Products you want to check, you can do something like:
SELECT c.ConsumerName
FROM tblConsumer AS c
WHERE c.ProductID IN (1,2,3)
GROUP BY c.ConsumerName
HAVING COUNT(DISTINCT c.ProductID) = (SELECT COUNT(DISTINCT p.ProductID) FROM tblProduct WHERE p.ProductID IN (1,2,3))
;
But I think maybe you just want to use NOT EXISTS to eliminate the Consumers for whom there's a record they haven't bought.
Like this:
SELECT *
FROM tblPerson AS pn CROSS JOIN tblProduct AS pt /* Every possible combo */
WHERE NOT EXISTS (SELECT * FROM tblConsumer c
WHERE c.ConsumerName = pn.ConsumerName
AND c.ProductID = pt.ProductID)
;

Answer 2

I have an other small solution:
SELECT * FROM tblConsumer
WHERE NOT EXISTS (SELECT * FROM tblProduct
LEFT JOIN tblConsumer C ON tblProduct.ProductID = C.ProductID AND tblConsumer .ConsumerName = C.ConsumerName
WHERE C.ConsumerName IS NULL)
It will work if you add a new entry too. It just checks, that is there any record, where you cant make a connection between the given Consumer and a Product.