使用PHP Order By对查询结果进行排序

Question

The below code displays data from a table and then filters it depending on the results of two combo boxes. I am able to order the results by ID once the form is submitted, but not on initial load (where all are listed). I have tried $sql = "SELECT * FROM Places ORDER BY ID"; which works when the list loads but returns an error when the form is submitted. Hope that makes sense. Any ideas? Thanks!

// Default query
$sql = "SELECT * FROM Places";
// check if form was submitted
if (isset($_POST['area'])) {
    $connector = 'where';
    if ($_POST['area'] != 'All') { 
        $sql .= " where Area = '".$_POST['area']."' ORDER BY ID";
        $connector = 'and';
    }
    if ($_POST['theme'] != 'All') { 
        $sql .= " $connector Theme = '".$_POST['theme']."' OR Theme2 = '".$_POST['theme']."' 
        ORDER BY ID";
    }
}

Answer 1

Your ORDER BY ID clause must appear at the very end of your statement. If both $_POST['area'] and $_POST['theme'] are filled, you end up with a query like this:

SELECT ... WHERE Area = 'some area' ORDER BY ID AND Theme = 'some theme'

Add the ORDER BY bit as the last part of your query.