How to insert point data into mysql using PDO bindParam?

Question

DETAILS

I'd like to make use of mysql's spatial extension, so I am trying to store longitude and latitude in a mysql table of datatype POINT using bindParam. Unfortunately, I keep getting the error SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'location' cannot be null.

I've checked that longitude and latitude have values. So the problem has to be with my code, but I cannot see what I am doing wrong.

Here is the code I am using.

$location=$latitude." ".$longitude;
$sql = "INSERT INTO my_geodata SET location = PointFromText('POINT(:location)')";
      //INSERT INTO my_geodata SET location = PointFromText('POINT(-41 12)');    

try 
{
    $stmt = $dbh->prepare($sql);            
    $stmt->bindParam(':location', $location, PDO::PARAM_STR);           
    $stmt->execute();   
    $dbh = null;
}

catch(PDOException $e)
{               
    echo $error=$e->getMessage();
}

QUESTION

What am I doing wrong? How can I insert longitude and latitude into a mysql table (that uses POINT datatype) with PDO and bindParam?

VARIATION

Based on AgreeOrNot's answer, a slightly different way to achieve this is

$location = 'POINT(' . $latitude . " " . $longitude . ')';    
$sql = "INSERT INTO my_geodata (location) VALUES (PointFromText(:location))";

Answer 1

Note that parameterizing queries is not (simple) string replacement. In your code your query parameter is put in a string literal which will be kept untouched.

Try this:

$location = 'POINT(' . $latitude . " " . $longitude . ')';
$sql = "INSERT INTO my_geodata SET location = PointFromText(:location)";