PHP: building query from array foreach

$test=$_POST['Cities'];
 foreach ($test as $t){
 $query .= " AND u.bostadsort = \'".$t."\'";
 }

I have this for my

<select size="6" name="Cities[]" multiple="multiple">
    <option value="">All</option>
    <option value="1">C1</option>
    <option value="2">C2</option>
    <option value="3">S3</option>
    <option value="4">S4</option>
    <option value="5">S5</option>
</select>

But its not right at all.

What I'm trying to do is when you pick the cities(in the search form), it puts all the values into an array.

Now I would like to have it write like this, if you e.g pick 2, 4, 5

AND u.bostadsort = '2' OR u.bostadsort = '4' OR u.bostads开发者_JAVA技巧ort = '5'

(maybe you could do this easier to, but this is the only way i know, using "OR")

So if you picked more than 1 then it should be OR, instead of the AND i got.

Maybe I done it in a wrong way, and there is a better method doing this than foreach..

How can I do this?

You could use IN instead, which lets you supply multiple values:

if (is_array($_POST['Cities']))
{
  // If multiple values were selected, handle them
  $cities = array();
  foreach ($_POST['Cities'] as $city)
  {
    if (!empty($city))
    {
      $cities[] = mysql_real_escape_string($city);
    }
  }
}
elseif (!empty($_POST['Cities']))
{
  // ... or was a single, non-empty value passed in?
  $cities = array(mysql_real_escape_string($_POST['Cities']));
}

if (count($cities))
{
  $query .= " AND u.bostadsort IN ('" . join("', '", $cities) . "')";
}

Note that I am passing each value through mysql_real_escape_string before using it in the query; this is done to prevent SQL injection. If you are not using MySQL, the other RDBMSes have similar functions.

See http://www.ideone.com/UVXuu for an example (ideone doesn't seem to have mysql enabled, so the calls to mysql_real_escape_string are removed).

Alternately, you could use PDO's prepare and execute methods:

$cities = $_POST['Cities'];
if (count($cities))
{
  $query .= " AND u.bostadsort IN (?" . str_repeat(', ?', count($cities) - 1) . ")";
}

// $db is a PDO object
$stmt = $db->prepare($query);
$stmt->execute($cities);

(Of course, this solution ignores how you build the rest of your query because you don't give it in your question, so you'd want to parameterize the other parts as well.)