Ajax & PHP: MySQL Query Not Fetching Any Rows

I have 3 combo boxes set to filter results from a MySQL database. On load, all the results are being shown in their proper order, but when I try to select any 1 out of the 3 combo boxes, or any 2 out of the 3 combo boxes, no results (rows) are displayed. If I select all 3 combo boxes, then results are shown.

I'm hoping someone can figure out what's wrong with my query code. I've tried everything and can't seem to find anything wrong with it. I also wonder if I am doing it in the best way. I'm fairly new to PHP, and so I don't know all the different methods available.

The PHP:

//Define Refine Data Values
$imgFamily = $_GET['imgFamily'];
$imgClass = $_GET['imgClass'];
$imgGender = $_GET['imgGender'];



//Define Refine Values as True of False
$imgFamilyTrue = (($imgFamily != 1) || ($imgFamily != null));
$imgFamilyFalse = (($imgFamily == 1) || ($imgFamily == null));

$imgClassTrue = (($imgClass != 1) || ($imgClass != null));
$imgClassFalse = (($imgClass == 1) || ($imgClass == null));

$imgGenderTrue = (($imgGender != 1) || ($imgGender != null));
$imgGenderFalse = (($imgGender == 1) || ($imgGender == null));



include"db.php";

//Database queries based on refine selections
if($imgFamilyFalse && $imgClassFalse && $imgGenderFalse) {
    $query_pag_data = "SELECT `imgURL`,`imgTitle` FROM `images` ".
    "ORDER BY `imgDate` DESC";

} else if($imgFamilyTrue && $imgClassTrue && $imgGenderTrue) {
    $query_pag_data = "SELECT `imgURL`,`imgTitle` FROM `images` WHERE imgFamily='$imgFamily' AND imgClass='$imgClass' AND imgGender='$imgGender' ".
    "ORDER BY `imgDate` DESC";

} else if($imgFamilyTrue && $imgClassFalse && $imgGenderFalse) {
    $query_pag_data = "SELECT `imgURL`,`imgTitle` FROM `images` WHERE imgFamily='$imgFamily' ".
    "ORDER BY `imgDate` DESC";

} else i开发者_Python百科f($imgFamilyFalse && $imgClassTrue && $imgGenderFalse) {
    $query_pag_data = "SELECT `imgURL`,`imgTitle` FROM `images` WHERE imgClass='$imgClass' ".
    "ORDER BY `imgDate` DESC";

} else if($imgFamilyFalse && $imgClassFalse && $imgGenderTrue) {
    $query_pag_data = "SELECT `imgURL`,`imgTitle` FROM `images` WHERE imgGender='$imgGender' ".
    "ORDER BY `imgDate` DESC";

} else if($imgFamilyFalse && $imgClassTrue && $imgGenderTrue) {
    $query_pag_data = "SELECT `imgURL`,`imgTitle` FROM `images` WHERE imgClass='$imgClass' AND imgGender='$imgGender' ".
    "ORDER BY `imgDate` DESC";

} else if($imgFamilyTrue && $imgClassFalse && $imgGenderTrue) {
    $query_pag_data = "SELECT `imgURL`,`imgTitle` FROM `images` WHERE imgFamily='$imgFamily' AND imgGender='$imgGender' ".
    "ORDER BY `imgDate` DESC";

} else if($imgFamilyTrue && $imgClassTrue && $imgGenderFalse) {
    $query_pag_data = "SELECT `imgURL`,`imgTitle` FROM `images` WHERE imgFamily='$imgFamily' AND imgClass='$imgClass' ".
    "ORDER BY `imgDate` DESC";
}

I'm pretty sure the problem is with the PHP as no errors are being called from the javascript side, and everything was working when I only had two combo boxes, but I will post my jQuery Ajax query, in case the problem is on that end.

The Ajax:

function loadData(imgFamily, imgClass, imgGender){
    $.ajax
    ({
        type: "GET",
        url: "filter_test.php",
        data: {imgFamily:imgFamily, imgClass:imgClass, imgGender:imgGender},
        success: function(msg) {
            $("#gallery_container").html(msg);
        },
        error: function(jqXHR, textStatus, errorThrown) {
        },
        complete: function() {
        }
    });
}

What a hideous mess. You should definitely clean that up:

$where_clauses = array();

$where_clauses[] = "1=1"; // default do-nothing clause

if ($_GET['imgFamily']) {
   $where_clauses[] = "imgFamily='$imgFamily'";
}
if ($_GET['imgClass']) {
   $where_clauses[] = "imgClass='$imgClass'";
}
if ($_GET['imgGender']) {
   $where_clauses[] = "imgFamily='$imgFamily'";
}

$clause = implode(' AND ', $where_clauses);
$sql = "SELECT imgURL, imgTitle FROM images WHERE $clause ORDER BY imgDate DESC";

In your true condition you say "if the value is not equal to 1 OR the value is not null". However, if the value IS equal to one it is not null, so you get true. If the value is null, it's not equal to one so you get true.

Problem:

$imgFamilyTrue = (($imgFamily != 1) || ($imgFamily != null));
$imgFamilyFalse = (($imgFamily == 1) || ($imgFamily == null));

Fix:

$imgFamilyTrue = $imgFamily != 1 && $imgFamily != null;
$imgFamilyFalse = !$imgFamilyTrue;

the reason why you dont get the results is because you are using the AND operator you are saying

if its A and B and C then fetch the results so when you choose 1 out of 3 or 2 out of the 3 combo-box values the condition is failed and you get no results

EXAMPLE

if(A && B && C)
  // do something

and you select two values B and C so the condition returns false

I couldn't choose a "correct" response from the above answers, as both Marc B's & James' answers were instrumental in creating a working code.

James' answer alone would have corrected the original code, however Marc B helped immensely in cleaning up the code, and making it more efficient. Props to both.

On top of their suggestions, I had to wrap the $where_clauses[] = "1=1" in an if condition where there was no usable data from the Ajax.

I also had to wrap the mysql_real_escape_string($_GET[]'s in single quotes to be usable in the MySQL query.

My final PHP:

//Define Refine Data Values
$imgFamily = $_GET['imgFamily'];
$imgClass = $_GET['imgClass'];
$imgGender = $_GET['imgGender'];



//Define Refine Values as True of False
$imgFamilyTrue = $imgFamily != 1 && $imgFamily != null;
$imgFamilyFalse = !$imgFamilyTrue;

$imgClassTrue = $imgClass != 1 && $imgClass != null;
$imgClassFalse = !$imgClassTrue;

$imgGenderTrue = $imgGender != 1 && $imgGender != null;
$imgGenderFalse = !$imgGenderTrue;



//where clauses
$where_clauses = array();

if ($imgFamilyFalse && $imgClassFalse && $imgGenderFalse) {
    $where_clauses[] = "1=1"; // default do-nothing clause
}

if ($imgFamilyTrue) {
   $where_clauses[] = 'imgFamily=' . "'" . mysql_real_escape_string($_GET['imgFamily']) . "'";
}
if ($imgClassTrue) {
   $where_clauses[] = 'imgClass=' . "'" . mysql_real_escape_string($_GET['imgClass']) . "'";
}
if ($imgGenderTrue) {
   $where_clauses[] = 'imgGender=' . "'" . mysql_real_escape_string($_GET['imgGender']) . "'";
}



include"db.php";


$clause = implode(' AND ', $where_clauses);


$query_pag_data = "SELECT imgURL, imgTitle FROM images WHERE $clause ORDER BY imgDate DESC";


$result_pag_data = mysql_query($query_pag_data) or die('MySql Error' . mysql_error());


$num_rows = mysql_num_rows($result_pag_data);


if(!$result_pag_data) {
    echo "Cannot retrieve information from database.";
} else if($num_rows == 0) {
    echo "<div id='no_result'>Sorry, there are no items matching your request.</div>";
} else { 
    echo "<ul class='new_arrivals_gallery'>";
    while($row = mysql_fetch_assoc($result_pag_data)) { 
        echo "<li><a target='_blank' href='new_arrivals_img/".$row['imgURL']."' class='gallery' title='".$row['imgTitle']."'><img src='new_arrivals_img/thumbnails/".$row['imgURL']."'></a></li>";
      }
    echo "</ul>";   
}