SQL 查询不显示每个子类别中的产品

Question

我试图在每个类别上显示一个产品，从顶级父类别一直到该类别。我有这样的数据库设置：

CATEGORY TABLE:
id  |  parent_id   |  root_cat   |  name
5       37              0            bulbs
45      5               0            standard auxiliary
289     45              5            standard
297     289             5            5W

现在这是产品表：

id    |   name    |   cat
470       bulb 5w      297

这种情况正在发生，当我单击灯泡类别时，我看到的产品很好，但是当我单击子类别标准辅助时，我看不到产品。但是，如果我达到标准的另一个级别，我可以再次看到该产品，并且如果我点击 5W 猫，我也可以看到该产品。所以问题只在标准辅助类上。

这是我用来检索数据的方法： $table_2 是产品表，$table 是类别表。

public function getProductsWhereParentIdis($cat) {
        $check = $this->checkCategoryChildren($cat);
        if($check) {
            $query = "
            SELECT * 
            FROM categories 
            INNER JOIN products 
            ON products.category = categories.id 
            WHERE categories.id = '".$this->db->escape($cat)."' 
            OR categories.parent_id = '".$this->db->escape($cat)."' 
            OR categories.root_category = '".$this->db->escape($cat)."'";   

            return $this->db->fetchAll($query);
        } else {
            $query = "SELECT * FROM {$this->table_2} WHERE category = '".$this->db->escape($cat)."'";

            return $this->db->fetchAll($query);
        }


    }

而且这个方法只是检查一个产品是否有父级：

public function checkCategoryChildren($id = null) {
        if(!empty($id)) {
            $query = "SELECT * FROM {$this->table} WHERE parent_id = '".$this->db->escape($id)."' ORDER BY view_order ASC";

            return $this->db->fetchAll($query);
        }
    }

这是 fetchAll 方法：

public function query($query) {
        $this->last_query = $query;
        $result = mysqli_query($this->connection, $query);
        $this->confirm_query($result);
        return $result;
    }

    public function confirm_query($result) {
        if(!$result) {
            $output  = "Database query failed<br />";
            $output .= "Last SQL query: ". $this->last_query;
            die($output);
        } else {
            $this->affected_rows = mysqli_affected_rows($this->connection);
        }
    }

    public function fetchAll($query) {
        $result = $this->query($query);
        $output = array();
        while($row = mysqli_fetch_assoc($result)) {
            $output[] = $row;
        }
        mysqli_free_result($result);
        return $output;
    }

真的很期待任何人的建议，为什么我可以在除一个之外的所有类别中看到该产品，谢谢。

Answer 1

这是我认为您正在寻找的解决方案 主要问题是您只看到仅上一级或下一级的类别数据

我还在代码中提到了一些 cmets，请检查一下。 而且我也不知道您的fetchAll() 函数如何返回数据。 例如。 object 或 array。

编辑：所以在这段代码中fetchAll()函数以数组格式返回数据，因为你使用了mysqli_fetch_assoc()

public function getProductsWhereParentIdis($cat)
{
    $check = $this->checkCategories($cat);
    if (!empty($check)) {
        $query = "
        SELECT * 
        FROM categories 
        INNER JOIN products 
        ON products.category = categories.id 
        WHERE categories.id in (".(implode(",", $check)).")";
        return $this->db->fetchAll($query);
    } else {
        $query = "SELECT * FROM {$this->table_2} WHERE category = '".$this->db->escape($cat)."'";

        return $this->db->fetchAll($query);
    }
}

public function checkCategories($cat_id)
{
    $query = "SELECT * FROM {$this->table} WHERE id = '".$this->db->escape($cat_id)."' ORDER BY view_order ASC";
    $catObj = $this->db->fetchAll($query);
    $childs = $this->getChildCategoryIds($cat_id);
    $childs[] = $cat_id;
    // you can remove the parents from here if you don't want to get all
    // products which have parents categories associated in it.
    // eg. while user click on standard then if you don't want to get the products which
    // is assigned with bulbs or standard auxiliary then return only childs.
    $parents = $this->getParentCategoryIds($catObj[0]['parent_id']);
    return array_merge($childs, $parents);
}

public function getChildCategoryIds($cat_id)
{
    $cat_array = [];
    $q = "SELECT * FROM {$this->table} WHERE parent_id = '".$this->db->escape($cat_id)."' ORDER BY view_order ASC";
    $result = $this->db->fetchAll($q);
    foreach ($result as $value) {
        $tmp_array = $this->getChildCategoryIds($value['id']);
        $cat_array[] = $value['id'];
        if (!empty($tmp_array)) {
            $cat_array = array_merge($cat_array, $tmp_array);
        }
    }
    return $cat_array;
}

public function getParentCategoryIds($cat_id)
{
    $cat_array = [];
    $q = "SELECT * FROM {$this->table} WHERE id = '".$this->db->escape($cat_id)."' ORDER BY view_order ASC";
    $result = $this->db->fetchAll($q);
    if (!empty($result[0]['parent_id'])) {
        $tmp_array = $this->getParentCategoryIds($result[0]['parent_id']);
        $cat_array[] = $result[0]['parent_id'];
        if (!empty($tmp_array)) {
            $cat_array = array_merge($cat_array, $tmp_array);
        }
    }

    return $cat_array;
}

Answer 2

FWIW，我觉得这更容易阅读......

SELECT c.olumms
     , i.actually
     , w.ant
  FROM categories c
  JOIN products p
    ON p.category = c.id 
 WHERE :mystring IN (c.root_category,c.parent_id,c.id);