Question

I am novice PHP programmer and I have created a function that changes an SQL command. Here is relevant piece of code:

 $extra_text_length = strlen($_GET[extra_text]);
 $boolean = $_GET['first-boolean'];

 function check_boolean(){

  if($extra_text_length > 0){

    if($boolean=="and"){
        $query .= " AND (software.SWID='$_GET[extra_text]')";
        } elseif($boolean=="or"){
        $query .= " OR (software.SWID='$_GET[extra_text]')";
        } elseif($boolean=="not"){
        $query .= " NOT IN (software.SWID='$_GET[extra_text]')";
        }
    } return $boolean;
  }

check_boolean();

The problem is that it doesn’t do what it should do. If I remove the code from the function however and as consequence I remove the check_boolean() method it works perfectly. Would anyone give me a hint? Thanks in advance

Answer 1

Make sure to use the variable name $boolean instead of boolean, otherwise it’s trying to get a constant.

You also have to be careful to what you pass to your method. $query is a variable that you haven’t defined either.

Make sure to do something like this

 $extra_text_length = strlen($_GET[extra_text]);
 $boolean = $_GET['first-boolean'];

 function check_boolean($query, $extra_text_length, $boolean, $software){

  if($extra_text_length > 0){

    if($boolean=="and"){
        $query .= " AND ($software.SWID='$_GET[extra_text]')";
        } elseif($boolean=="or"){
        $query .= " OR ($software.SWID='$_GET[extra_text]')";
        } elseif($boolean=="not"){
        $query .= " NOT IN ($software.SWID='$_GET[extra_text]')";
        }
    }
    return $query;
  }

$query = '...';
$software = '';
$query = check_boolean($query, $extra_text_length, $boolean, $software);

Also, avoid using external variables in a function, since you don’t know how they will react. ($_GET)
You should also check the existence of all your variables.