MySQL - 查询无法正常工作[关闭]

Here is my query:

if($GetSize != ""){
    $r = mysql_query("select * from `ProductSizes` ps, `products` p WHERE `ps.Size`='$GetSize' and `p.id`=`ps.Product`");

} else {
    $r = mysql_query("SELECT * FROM `products` WHERE `Category`='$Cat' $FilterSQL $FilterSQLS $BrandSearch ORDER $OrderBy LIMIT $first_product_shown1, $products_per_page");
}


while($rowi = mysql_fetch_array($r))
        {

        $id = $rowi['id'];
        $Title = $rowi['Title'];
        $Image = $rowi['Image'];
        $Price = $rowi['Price'];
        $PriceOld = $rowi['PriceOld'];
        $Rating = $rowi['Rating'];
        $SDProductCode = $rowi['ProductCode'];
        $Lev = $Price * GetSetting('PoundRate');
        $LevOld = $PriceOld * GetSetting('PoundRate');
        $Lev = number_format($Lev, 2, '.', '');
        $LevOld = number_format($LevOld, 2, '.', '');
}

I think i have some mistake in it because i get no results.

Do you find any mistake and how the fixed variant must look like ?

Thanks in advance!

You are using WHERE clause before JOIN:

Correction:

mysql_query("
select * from `ProductSizes` c 
join `products` o on o.`id` = c.`Product` 
WHERE `c.Size` = '$GetSize'
");

Side Note:

I suggest you to use mysqli_* or PDO instead of mysql_* becuase it's deprecated and not available in PHP 7.

Consider modifying your query like below cause your query syntax is wrong. JOIN clause should come before WHERE

select c.* 
from `ProductSizes`  c 
join `products` o on o.`id` = c.`Product`
WHERE c.`Size` = '$GetSize';  

SQL query seems to be incorrect... try this

mysql_query("select * from `ProductSizes` ps, `products` p WHERE `ps.Size`='$GetSize' and p.`id`=ps.`Product`")

Also a good idea to check MySQL query result using mysql_query_error function

if(mysql_query_error()) {
    //Probably syntax error
}

Try this

mysql_query("select * from `ProductSizes` c join `products` o on o.`id`=c.`Product` WHERE c.`Size`='$GetSize'")