(seemingly) simple SQL SELECT statement

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February 27th, 2007, 01:03 PM

fozzyuw

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(seemingly) simple SQL SELECT statement

Hey all,

I admit, I'm very bad with SQL. I'm trying to do something, that I would think would be easy, but I cannot get it right. I know this has to be" SQL 101", but, I've stuck. Here's the scoop.

3 tables.

products
--------
products_id
products_number
(other stuff)...

categories
----------
categories_id
categories_name
(other stuff)...

products_x_categories
----------------------
products_id
categories_id

How would I got about getting the products data from the table 'products' that have been assigned to two different categories (assigned to BOTH categories)?

Example data...

products
--------
1 MMT100
2 MMT200
3 XXT100
4 XXT200

categories
----------
1 "Foo"
2 "Bar"
3 "Goo"

products_x_categories
---------------------
1 1
1 2
2 1
2 3
3 1
3 2
4 3

Query = "Give me the products id and name that belong to BOTH 'foo' and 'bar';

result =
1 MMT100
3 XXT100

So, how would I write that SQL?

Cheers!
Fozzy

*edit* spelling/grammer

February 27th, 2007, 02:41 PM

Itsacon

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I think you want something like this:

MySQL Code:

Original - MySQL Code
SELECT * FROM products WHERE 2 == (SELECT COUNT(*) FROM products_x_categories INNER JOIN categories ON (categories.id = products_x_categories.category_id) WHERE categories.name IN('foo', 'bar') AND products_x_categories.product_id = products.id GROUP BY products_x_categories.product_id);

SELECT * 
FROM products 
WHERE 2 == (SELECT COUNT(*)
    FROM products_x_categories
        INNER JOIN categories ON (categories.id = products_x_categories.category_id)
    WHERE categories.name IN('foo', 'bar')
        AND products_x_categories.product_id = products.id
    GROUP BY products_x_categories.product_id);

Didn't test for syntax errors, so it may not work out of the box.

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This is my code. Is it not nifty?

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February 27th, 2007, 03:57 PM

fozzyuw

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Thanks for the response Itsacon,

I don't think that's exactly what I'm looking for. It appears there's a condition that is (2 == ...) which, in my case, can me anything more than two.

I did find another solution, which required using an extra field as a check, which wasn't used before.

Thanks for the help mate!

Cheers,
Fozzy

February 28th, 2007, 04:50 AM

Itsacon

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the "2 ==" can of course be replaced by "1 <", so you get everything with two or more entries.

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