PHP - include a php file and also send query parameters
Imagine the include as what it is: A copy & paste of the contents of the included PHP file which will then be interpreted. There is no scope change at all, so you can still access $someVar in the included file directly (even though you might consider a class based structure where you pass $someVar as a parameter or refer to a few global variables).
You could do something like this to achieve the effect you are after:
$_GET['id']=$somevar;include('myFile.php');
However, it sounds like you are using this include like some kind of function call (you mention calling it repeatedly with different arguments).
In this case, why not turn it into a regular function, included once and called multiple times?
An include is just like a code insertion. You get in your included code the exact same variables you have in your base code. So you can do this in your main file :
<? if ($condition == true) { $id = 12345; include 'myFile.php'; }?>
And in "myFile.php" :
<? echo 'My id is : ' . $id . '!';?>
This will output :
My id is 12345 !