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POMySQL: count votes for users
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copied!<p>I'm searching for a way to count votes for a user in a MySQL database.</p> <p><strong>Tables and Columns:</strong></p> <pre><code>companion - companion_id - news_id - user_id news - news_id - user_id user - user_id - user_name vote - vote_id - news_id - user_id </code></pre> <p>check out the <strong><a href="http://sqlfiddle.com/#!2/841d9f/14" rel="nofollow">SQL Fiddle Live Demo</a></strong></p> <p><strong>Conditions:</strong></p> <ul> <li>every <em>user</em> can have several <em>news</em></li> <li>every <em>news</em> can have several <em>votes</em></li> <li>every <em>news</em> can have several <em>companions</em> (companions are user)</li> <li>every <em>user</em> can vote for several <em>news</em> (not important for this query)</li> </ul> <p><strong>Target:</strong></p> <p>Now I'm trying to figure out how many votes a user has together: on his own news an on which he is linked as a companion. The solution should be a <strong>single</strong> MySQL query.</p> <p><strong>Example for <em>User2</em>:</strong></p> <ul> <li><em>User2</em> has <strong>1</strong> news article. This news article has <strong>2</strong> votes.</li> <li><em>User2</em> is companion of <strong>1</strong> article. This news article has <strong>3</strong> votes.</li> <li><em>User2</em> should have <strong>5</strong> votes </li> </ul> <p><strong>Approach:</strong></p> <p>The following query results 31 and not 5, because it can't group it correct over 2 differnt tables.</p> <pre><code>SELECT u.user_name, u.user_id, COUNT(v.vote_id) AS votes FROM user u, news n, companion c, vote v WHERE u.user_id = 2 AND ( ( u.user_id = n.user_id AND n.news_id = v.news_id ) OR ( u.user_id = c.user_id AND c.news_id = v.news_id ) ) GROUP BY u.user_id LIMIT 1 </code></pre>

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