Prestashop 1.5.6.2 shows wrong products in category (FrontOffice)

I am using prestashop 1.5.6 and doing bulk category and product manipulation in mysql through 3rd party libraries (which I wrote). All is well until some of my products show up in the wrong category. For example, I have product A in category A; But when I go to Product B of Category A, there is also. I think there is something wrong with my table ps_category_product

with position column. I am updating this table with the code below;

$sqlFirst = 'SELECT id_product, id_category_default, xml_id_product FROM ps_shop_product';
$queryFirst = $db->prepare($sqlFirst);
$queryFirst->execute();
while ($rowFirst = $queryFirst->fetch(PDO::FETCH_OBJ)){ 
    $sqlProductAddCatPosFirst = '
        INSERT INTO ps_shop_category_product
        (id_product, id_category, position)
        VALUES 
        (?, ?, ?)
        ';
    // ps_shop_category_product Sql sorgumuzu hazırlayalım
    $queryProductAddCatPosFirst = $db->prepare($sqlProductAddCatPosFirst);
    $queryProductAddCatPosFirst->bindParam(1, $rowFirst->id_product, PDO::PARAM_INT);
    $queryProductAddCatPosFirst->bindParam(2, $rowFirst->id_category_default, PDO::PARAM_INT);
    $queryProductAddCatPosFirst->bindParam(3, $rowFirst->id_product, PDO::PARAM_INT);
    // ps_shop_category_product Hazır Sql sorgumuzu çalıştıralım
    $queryProductAddCatPosFirst->execute();
}

      

        
        
        
      

    

But everything is fine on the tab Backoffice > Products > Filter By Category

. It shows the correct products under the category. Are there any specific details in Front Office? If I truncate the table (ps_category_product)

, my products are not showing up in categories in Front Office. What am I missing?

Any help would be very helpful.

Update

Following @bcsteeve's comment, I create a sample category from BackOffice and all products listed in the correct categories. When I look at changes in my mysql tables; only the table ps_category

changed some of the column values nleft

and nright

.

In my simple web service, I assign nleft

and the nright

value 0 (zero). But now they have some values ​​other than 0 (zero).

Now I think my problem is recalculating the table hierarchy ps_category

.

Is there any particular main controller and / or method that can recalculate the nleft and nright values ​​in the table ps_category

? Because I don't want to add a category manually after my webservice has updated my products and categories.

Thanks in advance!