PHP variables don’t evaluate in the query [duplicate]

This happens when your result is not a result (but a “false” instead). You should change this line

$sql = 'SELECT * FROM $usertable WHERE PartNumber = $partid';

to this:

$sql = "SELECT * FROM $usertable WHERE PartNumber = $partid";

because the ” can interprete $variables while ‘ cannot.

Works fine with integers (numbers), for strings you need to put the $variable in single quotes, like

$sql = "SELECT * FROM $usertable WHERE PartNumber = '$partid' ";

If you want / have to work with single quotes, then php CAN NOT interprete the variables, you will have to do it like this:

 $sql = 'SELECT * FROM '.$usertable.' WHERE string_column = "'.$string.'" AND in