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POMySQL query WHERE statement which is a query itself?
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copied!<p>So I'll try to clearly explain my goal first:</p> <p>First, I want to query one table in my database for a list of usernames.</p> <p>Second, I want to take those usernames, and query another table in the database and return only the rows in which these usernames appear in the username field.</p> <p>Finally, I want to take this output (in JSON array form right now), and return it to the requesting client.</p> <p>My query looks like this right now:</p> <pre><code>$query = mysql_query("SELECT * FROM tagusers WHERE username = (SELECT userA FROM friendtable WHERE userB = '$username')"); </code></pre> <p>This works when the WHERE statement yields 1 result. So if I only get one returned userA, it works fine. But if I get multiple, I get a bunch of errors.</p> <p>Here is the code in its entirety:</p> <pre><code>if (isset($_POST['username'])) { $username = $_POST['username']; $connect = mysql_connect("localhost", "root", ""); mysql_select_db("TagDB"); $query = mysql_query("SELECT * FROM tagusers WHERE username = (SELECT userA FROM friendtable WHERE userB = '$username')"); } while ($e = mysql_fetch_assoc($query)) { $output[] = $e; } $output = json_encode($output); print $output; </code></pre> <p>I get the following error on the query line:</p> <p>*Warning: mysql_query() [function.mysql-query]: Unable to save result set in C:\wamp\www\tag\appgetfriendinfo.php on line 21*</p> <p>So all I really need to know is, how would I write that query in MySQL so that I get returned an array of rows?</p>

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