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Archive for September 8th, 2009

MySQL: matching whole sets

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From Stack Overflow:

I have a database that stores products available on the market and products still in development in two separate tables (market_product and dev_product).

A third table (substance) contains all substances a product can made of.

Other two tables (marked_product_comp and dev_product_comp) mantains product compositions.

I want to select products still in development that are made of the same ingredients of marketed products.

This means that we need to return every dev_product that has at least one market_product with complete substance match.

In the following example:

DevProductID Substance
1 Apple
1 Banana
2 Apple
2 Banana
2 Cabbage
MarketProductID Substance
1 Apple
2 Apple
2 Banana
3 Apple
3 Banana
3 Cabbage
3 Daikon

we should return development product 1, since it's made of apples and bananas, and there is at least one product already on market (namely, market product 2) that is made of exactly same things and nothing else.

We should not return development product 3, because these is no complete match with market product 3, since is daikons are used to make the latter but not the former.

In one of the previous articles I wrote about a similar task in SQL Server:

However, this used FULL OUTER JOIN which MySQL lacks.

Let's see how to implement this task in MySQL:

Read the rest of this entry »

Written by Quassnoi

September 8th, 2009 at 11:00 pm

Posted in MySQL