MySQL Limit with Many to Many Relationship

Question

Given a SCHEMA for implementing tags

ITEM ItemId, ItemContent

TAG TagId, TagName

ITEM_TAG ItemId, TagId

What is the best way to limit the number

Answer 1

My first suggestion is to use a subquery to generate the list of item ID's and return items matching those item ID's. But this doesn't include the TagName in your result set. I'll submit a separate answer with another solution.

SELECT i.ItemContent
FROM item AS i
WHERE i.id IN (
  SELECT it.ItemId
  FROM ItemTag AS it
    INNER JOIN tag AS t ON (t.id = it.TagId)
  WHERE t.TagName IN ('mysql', 'database', 'tags', 'tagging')
);

This is a non-correlated subquery, so a good SQL engine should factor it out and run it only once.