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POHow does SO calculates number of votes, answers and views in database?
 

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  1. POHow does SO calculates number of votes, answers and views in database?
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    <p>I think SO and other question/answer systems are perfect example for advanced TSQL techniques. I am wondering how SO and other questions/answers systems work with DB tables. I am particulary interested what is the TSQL select for list of questions where you also want to show number of votes and answers. </p> <p>Table <code>question</code> would be specified as this</p> <pre><code>id int title varchar id_user int </code></pre> <p>table <code>votes</code> so you can monitor users votes for particular question</p> <pre><code>id_user int id_question int vote int </code></pre> <p>table 'answer' with replies to question</p> <pre><code>id int id_parent int </code></pre> <p>What would select look like to get result from <code>question</code> like this:</p> <pre><code>id int title varchar votes_count int answers_count int </code></pre> <p>I was thinking about two methods</p> <ol> <li>Table <code>question</code> would recalculate with every vote or answer and update table fields <code>votes_count</code> and <code>answers_count</code> directly in <code>question</code> table. That means table <code>question</code> would have also <code>votes_count int, answers_count int</code></li> <li>Create select which would join, calculate <code>count</code> directly in <code>votes</code> or <code>answers</code> tables and just show results in <code>question</code> table. How much speed would be lost by counting with every select all the records for votes and answers?</li> </ol> <p>Thanks.</p>
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