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    <p>Since you're asking about good practices... the "upvotes" and "downvotes" appearing in your Posts table looks like you're duplicating data in your database. That's a problem, because now you always have to worry whether or not the data is in sync and correct. If you want to know the number of upvotes then count them, don't also store them in the Post table. I'm not positive that is what you're doing, but it's a guess.</p> <p>Onto your query... You will probably get better performance using a JOINed subquery instead of how you have it. With the scalar subqueries as columns they have to be run once for every row that is returned. That could be a pretty big performance hit if you're returning a bunch of rows. Instead, try:</p> <pre><code>SELECT P.id, P.name, P.body, P.upvotes, P.downvotes, COALESCE(UV.cnt, 0) AS upvotes2, COALESCE(DV.cnt, 0) AS downvotes2 FROM dbo.Posts P LEFT OUTER JOIN (SELECT post_id, COUNT(*) cnt FROM dbo.UpVotes GROUP BY post_id) AS UV ON UV.post_id = P.id LEFT OUTER JOIN (SELECT post_id, COUNT(*) cnt FROM dbo.DownVotes GROUP BY post_id) AS DV ON DV.post_id = P.id </code></pre> <p>Compare it to your own query and see if it gives you better performance.</p> <p>EDIT: A couple of other posters have advocated a single table for up/down votes. They are absolutely correct. That makes the query even easier and also probably much faster:</p> <pre><code>SELECT P.id, P.name, P.body, P.upvotes, P.downvotes, SUM(CASE WHEN V.vote_type = 'UP' THEN 1 ELSE 0 END) AS upvotes2, SUM(CASE WHEN V.vote_type = 'DOWN' THEN 1 ELSE 0 END) AS downvotes2, FROM dbo.Posts P LEFT OUTER JOIN Votes V ON V.post_id = P.id GROUP BY P.id, P.name, P.body, P.upvotes, P.downvotes </code></pre>
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    1. POIs this SQL select code following good practice?
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    1. COLEFT OUTER JOIN doesnt do what mine does. I am checking if i upvoted/downvotes the post by looking at my IP (its an fmylife like site which like a wiki doesnt require login). Isnt the () part in the outer join mean its doing a subquery? also when you say 'run once for every row that is returned' isnt that the same as a join which is applied on every row?
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    2. COoh and the up/down count is maintained by triggers on insert, update and remove. There should never be a case where it is wrong but it isnt important and i figure i can run checks later on.
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    3. CONope, a JOIN is most definitely not the same - SQL deals with sets and a JOIN is a set operation, so it is much faster. Although there is a subquery, that query is only run once in this case and the results are then kept until SQL is done with them - it's because they're different kinds of subqueries (correlated vs. non-correlated). As for the triggers and the data never getting out of sync, I'll just say, "famous last words" ;)
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