Question

I’ve got this code and I don’t know how to order my query

function get_All_Categories(){
//new instance of mysqli
    $mysqli = new mysqli(DB_SERVER, DB_USER, DB_PASSWORD, DB_NAME);
    //if it doesn't work give an error
    if (!$mysqli) {
        die('There was a problem connecting to the database.');
    }
    $queryCats ="SELECT Catid, Catname
                 FROM ProductCats
                 ORDER BY Catid";
    $querySubCats ="SELECT Subcatname, Parentid
                    FROM ProductSubCats, ProductCats
                    WHERE ProductSubCats.Parentid = ProductCats.Catid
                    ORDER BY Subcatname;";
    if ($catResults = $mysqli->query($queryCats)){
        if (!$catResults) {
            echo 'Could not run query: ' . mysql_error();
            exit;
        }
        else{
            $subCatResults = $mysqli->query($querySubCats);
        }
        while ($rows = $catResults->fetch_assoc()) {
            echo '<div class = "categoryCluster">';
            echo '<a href="../index.php?Cat='.$rows["Catname"].'">'.$rows["Catname"].'</a>';
            echo '<br>';
            while($rowsSub = $subCatResults->fetch_assoc()){
                echo '<div class="subCategoryCluster">';
                echo '&emsp;'.'<a href="../index.php?Cat='.$rows["Catname"].'&'.'Subcat='.$rowsSub["Subcatname"].'">'.$rowsSub["Subcatname"].'</a>';
                echo '<br>';
                echo '</div>';
            }
            echo '</div>';
        }
    }
    $mysqli->close();
}

Which displays this output:

Header 1
 Subcat 1
 Subcat 2
 OtherSubcat 1
Header 2
Header 3
Header 4
Header 5
Header 6

But my problem is that subcat 1 and subcat 2 have the parentid of 1, which conforms to header 1, however othersubcat 1 has the parentid of 5. Which actually conforms to header 5.
Yeh in my loop it is displaying right after the other 2.

Now I know why this is wrong, it is because the while loop in the while loop is ordering it to appear last, and sticking it in there.

But I have absolutely no idea how to rework this so that it would display:

Header 1
 Subcat 1
 Subcat 2
Header 2
Header 3
Header 4
Header 5
 OtherSubcat 1
Header 6

Sample table:

>     ProductSubCats
>     Subcatid  |  Subcatname   | Parentid
>     1         | Subcat 1      | 1
>     2         | Subcat 2      | 1
>     3         | Othersubcat 3 | 5
> 
> 
> 
> ProductCats
>     Cat id   |   Catname
>     1        | Header 1
>     2        | Header 2
>     3        | Header 3
>     4        | Header 4
>     5        | Header 5
>     6        | Header 6

Thank you for your help

Answer 1

For what you are trying to do, following off what @Pasha Bitz said.

Try the following:

$categories = array();
        $sub_categories = array();  
        while ($rows = $catResults->fetch_assoc()) {
            $categories[$rows['Catid']] = $rows['Catname'];
        }
        while($rows = $subCatResults->fetch_assoc()){
            if (!isset($sub_categories[$rows['Parentid']])) {
                $sub_categories[$rows['Parentid']] = array();
            }
            $sub_categories[$rows['Parentid']][] = $rows['Subcatname'];
        }
        foreach ($categories as $cat_id => $name) {
            echo '<div class = "categoryCluster">';
            echo '<a href="../index.php?Cat='.$name.'">'.$name.'</a>';
            echo '<br>';
            if (isset($sub_categories[$cat_id])) {
                foreach($sub_categories[$cat_id] as $cat_id => $sub_cat_name) {
                    echo '<div class="subCategoryCluster">';
                    echo '&emsp;'.'<a href="../index.php?Cat='.$name.'&'.'Subcat='.$sub_cat_name.'">'.$sub_cat_name.'</a>';
                    echo '<br>';
                }
            }
        }

That should resolve this for you, study the code so you understand what is going on here.