I have a PHP script, that calls a python script by
$call_python = \"python ../python/lp_3.py \".$author;
$python_output = Null;
$mystring = exec($call_python
In your PHP code, you're just calling "python", and letting PHP decide which version of Python to use. Use an explicit path to a specific Python binary, (e.g. /usr/bin/python2.6).
You need to know the exact path to the version of Python that has MySQLdb installed.
$call_python = "/opt/local/bin/python2.6 ../python/lp_3.py ".$author;
$python_output = Null;
$mystring = exec($call_python, $output_python);
did the job. Like @AJ pointed out, I had to tell python which version to chose. I chose a version where MySQLdb was available and all was fine.