Using a Parameter for Selection
On the next page, where we specify selection criteria, we are going to use the parameter we defined earlier. In SQL terms, this is equivalent to a selection clause of
WHERE Film = :P1
Note that the parameter name begins with a colon character, to indicate that we are comparing Film to the value of the P1 variable, not to the string “P1”.
Note also that Film does not appear in the Field name: drop down list. You must enter Film into the box manually.