Fermi energy is difference of energies of highest and lowest occupied single state particle. But, Fermi level is the sum of total energy of a particle (i.e) the sum of kinetic and potential energies.

What's the difference between Fermi Energy and Fermi Level?
i am having a slight problem with passing php-variables to a stroed procedure call from a php-script. Here comes the details:

This is how it works very perfect - passing the params as string:

$myHTML = $wpdb-&gt;query( 'CALL show_average_time_spent(2, "2011-10-24", "2011-10-24", @myHTML)' );


Brings back a perfect result.

And this is how it not works and throws the error (passing params as variables):

$date_from = '2011-10-24';
$date_to = '2011-10-27';
$myHTML = $wpdb-&gt;query( 'CALL show_average_time_spent(2, $date_from, $date_to, @myHTML)' );


throws this error:


  WordPress database error: [Unknown column '$date_from' in 'field list']
  CALL show_average_time_spent(2, $date_from, $date_to, @myHTML)


The $date_from is only used in this php-script for holding the selected date.

i realy appreciate any kind of help with this issue.

Thanks to all of you trying to help solving this problem.

Cheers,
Joe
