Question

I’m counting the right answers field of a table and saving that calculated value on another table. For this I’m using two queryes, first one is the count query, i retrieve the value using loadResult(). After that i’m updating another table with this value and the date/time. The problem is that in some cases the calculated value is not being saved, only the date/time.

queries look something like this:

        $sql = 'SELECT count(answer)

                FROM #_questionsTable
                WHERE 

                    answer = 1

                    AND

                    testId = '.$examId;

        $db->setQuery($sql);

        $rightAnsCount = $db->loadResult();

        $sql = 'UPDATE #__testsTable

                SET finish = "'.date('Y-m-d H:i:s').'", rightAns='.$rightAnsCount.'

                WHERE testId = '.$examId;

        $db->setQuery($sql);

        $db->Query();

answer = 1 means that the question was answered ok.

I think that when the 2nd query is executed the first one has not finished yet, but everywhere i read says that it waits that the first query is finished to go to the 2nd, and i don’t know how to make the 2nd query wait for the 1st one to end.

Any help will be appreciated. Thanks!

Answer 1

1. a PHP MySQL query is synchronous ie. it completes before returning – Joomla!’s database class doesn’t implement any sort of asynchronous or call-back functionality.

2. While you are missing a ‘;’ that wouldn’t account for it working some of the time.

3. How is the rightAns column defined – eg. what happens when your $rightAnsCount is 0

4. Turn on Joomla!’s debug mode and check the SQL that’s generated in out the profile section, it looks something like this

eg.

Profile Information

Application afterLoad: 0.002 seconds, 1.20 MB
Application afterInitialise: 0.078 seconds, 6.59 MB
Application afterRoute: 0.079 seconds, 6.70 MB
Application afterDispatch: 0.213 seconds, 7.87 MB
Application afterRender: 0.220 seconds, 8.07 MB
Memory Usage

8511696
8 queries logged.

SELECT * 
      FROM jos_session 
      WHERE session_id = '5cs53hoh2hqi9ccq69brditmm7'
DELETE 
      FROM jos_session 
      WHERE ( TIME < '1332089642' )
etc...