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xtrasmal/relational-division.sql

Created May 26, 2013 20:16
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MySQL Relational division
Raw
relational-division.sql
SELECT Products.*
FROM Products
JOIN ProductTags ON Products.id = ProductTags.product_id
WHERE ProductTags.tag_id IN (1,2,3)
GROUP BY Products.id
HAVING COUNT(DISTINCT ProductTags.tag_id) = 3
/*
Assuming that there is a unique
constraint on product_id,tag_id you
don't need the DISTINCT
*/
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