Issue with table JOIN query

[HDFilmMaker2112]

The below should be getting information from $tbl_name3 to ORDER the information gotten from $tbl_name.

 

$tbl_name is the products table. $tbl_name3 is the reviews table. I need to get the review_product_rating from the reviews table and order the products by the review_product_rating.

$sql30 = "SELECT * FROM $tbl_name JOIN $tbl_name3 USING(product_id) WHERE product_category='$cat' ORDER BY $sort_by_selected2 LIMIT $start, $limit";
$result30 = mysql_query($sql30) or die("Problem with the query: $sql30<br />" . mysql_error());

 

That code is returning no results, but the query itself isn't throwing any errors.

 

 

EDIT: something else I just remembered is, the review_product_rating stored in the DB is for each individual review, so I will need to also AVG the review_product_rating results for each products.

[HDFilmMaker2112]

Well I narrowed down the problem to being that there are no reviews in the reviews table. So I did this:

if($_GET['sort_by']=="rating_lh" || $_GET['sort_by']=="rating_hl"){
$sql30 = "SELECT * FROM $tbl_name JOIN $tbl_name3 USING(product_id) WHERE product_category='$cat' ORDER BY $sort_by_selected2 LIMIT $start, $limit";
$result30 = mysql_query($sql30) or die("Problem with the query: $sql30<br />" . mysql_error());
if(mysql_num_rows($result30)==0){
$sort_by_selected2="product_id";
$sql30 = "SELECT * FROM $tbl_name WHERE product_category='$cat' ORDER BY $sort_by_selected2 LIMIT $start, $limit";
$result30 = mysql_query($sql30) or die("Problem with the query: $sql30<br />" . mysql_error());
}
}
else{
$sql30 = "SELECT * FROM $tbl_name WHERE product_category='$cat' ORDER BY $sort_by_selected2 LIMIT $start, $limit";
$result30 = mysql_query($sql30) or die("Problem with the query: $sql30<br />" . mysql_error());
}

 

It's only returning the one product with the review though... I want the products that don't have a review to be listed after the first one. I guess the best work around is to generate a blank review, when ever a new product is entered into the system.