Killing a MySQL query during execution with PHP and AJAX

Question

I am creating a custom query builder, when user has created his query he can verify the query syntax by clicking a button. When the user click on the button to verify, An A

Answer 1

I believe that thread_id reported by CONNECTION_ID() is the same as the thread id used in mysqladmin....

You'd need to capture the process id for the connection before starting the query...

$qry="SELECT CONNECTION_ID() AS c";
$row=mysql_fetch_assoc(mysql_query($qry));
$_SESSION['mysql_connection_id']=$row['c'];

then when the user clicks the button do something like....

exec('mysqladmin -u $user -p$password killproc ' 
          . $_SESSION['mysql_connection_id']);

But this opens up the possibility of users killing other peoples' queries. You could inject a comment key, e.g. the php session id, at the beginning of each query (mysqladmin truncates text of the query) then use mysqladmin processlist to check the ownership and/or retrieve the thread id before killing it.