If Else only choosing first option [duplicate]

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I am trying to set up an If Else statement which decides which MYSQL query to use depending on the values submitted in a form.

The problem i am having is that know matter what values I send in the form, even if they are not "ALL" only the first query ever gets called.

Here is my code

 if($department = 'ALL' && $property_type = 'ALL')

 } elseif ($department = 'ALL'){