how to select all results from a column in database - php

Question

I have a form with a select field:
<select class="indexSearchLocationList" name="locationList">
<option value="allLocations">Anywhere in London</option>
<option value="barking_and_dagenham">Barking and Dagenham </option>
<option value="barnet">Barnet</option>
What im trying to do is if the user chooses the option allocations (Anywhere in London) then I need to use that to select all when querying the database below is the php I currently have but how do I specifiy if that particular option is choosen:
$choosenLocation = $_POST['locationList'];

Answer 1

Just try this, if it is not meet your requirement, then add your requirement briefly as comment.
$choosenLocation = $_POST['locationList'];
if($choosenLocation == 'allLocations')
{
$query = "select * from TABLE ";
}
else
{
$query = "select * from TABLE WHERE condition="any_condition";
}

Answer 2

I think that may be
if(isset($_POST['locationList']) & $_POST['locationList']=='allLocations')
{
$query = "select * from TABLE ";
//based on the mysqli_ or PDO you execute
//fetch the row and display accordingly
}

Answer 3

Do you expect something similar,
$choosenLocation = $_POST['locationList'];
if(isset($choosenLocation) && $choosenLocation == 'allLocations'){
$query = "select * from TABLE ";
//based on the mysqli_ or PDO you execute
//fetch the row and display accordingly
}else{
$query = "select * from TABLE WHERE condition='your condition here' " ;
}