How to have no value selected in an HTML form that queries a MYSQL database?

[TopGearFan]

I have an HTML form with multiple drop down boxes that the user selects and it then posts to a PHP page where they are used as $_post variables to query the database and display results. The problem is, I don't want a default value if nothing is selected passed to the PHP form.

<select name="City">
<option value="">Cities</option>
<option value="New York">New York</option>
<option value="Toronto">Houston</option>
</select>

<select name="Country">
<option value="" >Countries</option>
<option value="United States">Oil & Gas</option>
<option value="Canada">Retail</option>
</select>

For example, if they don't select a city I just want to run only the Countries dropdown box, but apparently it will use the blank value from the City option which messes up the query. I need to either diable the first option or maybe pass some variable that is like set to search ALL or something if that makes sense.

[bradgrafelman]

For one, you should add a 'selected="selected"' attribute to the default options to ensure that they are in fact the default options.

Next, those default options both have a value of an empty string, so presumably you should be checking to see if $_POST['City'], for example, is both set ([man]isset/man) and non-empty ([man]empty/man or [man]strlen/man) before you use its value. If either isn't true, then you can modify the query accordingly.