mysql - 获取连接表不起作用 codeigniter

Question

当我使用 $this->db->where() 和 $this->db->join() 时，它没有检索任何数据。当 var dump 显示 NULL 时。

在我的旧代码上，它工作正常，在查询中使用 JOIN 。无法弄清楚我缺少什么。

旧代码运行良好

public function get_admin_category($category_id) {
$language_id = $this->check_language();

$query = $this->db->query("SELECT DISTINCT *, (SELECT GROUP_CONCAT(cd1.name ORDER BY level SEPARATOR '  >  ') FROM " . $this->db->dbprefix . "category_path cp LEFT JOIN " . $this->db->dbprefix . "category_description cd1 ON (cp.path_id = cd1.category_id AND cp.category_id != cp.path_id) WHERE cp.category_id = c.category_id AND cd1.language_id = '" . (int)$language_id . "' GROUP BY cp.category_id) AS path, (SELECT DISTINCT keyword FROM " . $this->db->dbprefix . "url_alias WHERE query = 'category_id=" . (int)$category_id . "') AS keyword FROM " . $this->db->dbprefix . "category c LEFT JOIN " . $this->db->dbprefix . "category_description cd2 ON (c.category_id = cd2.category_id) WHERE c.category_id = '" . (int)$category_id . "' AND cd2.language_id = '" . (int)$language_id . "'");

return $query->row_array();
}

我尝试过的新代码。

public function get_admin_category($category_id) {
    $language_id = $this->check_language();
    $this->db->select('GROUP_CONCAT(cd1.name ORDER BY level SEPARATOR "  >  ")');
    $this->db->distinct();
    $this->db->from($this->db->dbprefix . 'category_path cp', 'LEFT');
    $this->db->join($this->db->dbprefix . 'category_description cd1', 'cp.path_id = cd1.category_id AND cp.category_id != cp.path_id', 'LEFT');
    $this->db->where('cp.category_id', 'c.category_id');
    $this->db->where('cd1.language_id', $language_id);
    $query = $this->db->get();
    return $query->row_array();
}

如何将旧的 $this->db->query 转换为与连接一起使用的 codeigniter。 http://www.codeigniter.com/userguide2/database/active_record.html

Answer 1

试试这个，它会对你有用。

$this->db->select("DISTINCT *,(SELECT GROUP_CONCAT(cd1.name ORDER BY level SEPARATOR '  >  ') FROM " . $this->db->dbprefix . "category_path cp LEFT JOIN " . $this->db->dbprefix . "category_description cd1 ON (cp.path_id = cd1.category_id AND cp.category_id != cp.path_id) WHERE cp.category_id = c.category_id AND cd1.language_id = '" . (int)$language_id . "' GROUP BY cp.category_id) AS path, (SELECT DISTINCT keyword FROM " . $this->db->dbprefix . "url_alias WHERE query = 'category_id=" . (int)$category_id . "') AS keyword", false);
$this->db->from($this->db->dbprefix . "category c");
$this->db->join($this->db->dbprefix . "category_description cd2", "c.category_id = cd2.category_id", "left");
$this->db->where("c.category_id", intval($category_id));
$this->db->where("cd2.language_id", intval($language_id));
$result = $this->db->get()->row_array();
return $result;