Php MYSQL query problems

Question

Okay so this problem is really boggeling my mind... I have a MYSQL query I want to make so that my php program can access and update the database with lat and long coordinates of a user and im getting issues...

This is non working code:

$currUsername = strtolower($_SESSION['username']);
$sql= "UPDATE users SET pos_Lat=$latitude, pos_Long=$longitude WHERE username=$currUsername";
$result = mysql_query($sql, $link);

The working code

$currUsername = "email_that_is_returned"
$sql= "UPDATE users SET pos_Lat=$latitude, pos_Long=$longitude WHERE username=$currUsername";
$result = mysql_query($sql, $link);

Is this because session returns data that is not able to be placed inside a query?

Answer 1

Check whether the session was started or not. if not started then add the following code to your page and then check its working or not.. i thing your session does not return any value.. so start session by using the code session_start();

session_start(); 
$currUsername = strtolower($_SESSION['username']);
$sql= "UPDATE users SET pos_Lat=$latitude, pos_Long=$longitude WHERE username=$currUsername";
$result = mysql_query($sql, $link);

Answer 2

You can check what type of data it is returning.

print $_SESSION['username'] .

Also there is a chance to break the SQL query if the $_SESSION['username'] returns data with spaces. Make sure the SQL query not failing even if the $_SESSION['username'] contains spaces and singlequotes etc..