方法有很多种。
例1:
$result = $this->db
->select('m.name, m.id, c.id, c.name')
->distinct()
->join('default_ps_products_manufacturers m', 'p.manufacturer_id=m.id')
->join('default_ps_product_x_cats x', 'p.id=x.product_id')
->join('default_ps_products_categories c', 'x.category_id=c.id')
->get('default_ps_products p')
->result();
echo $this->db->last_query();
有时活动记录不能产生想要查询。所以,你可以把它写自己。
实施例2:
$query = "SELECT DISTINCT m.name, m.id, c.id, c.name
FROM `default_ps_products` p
INNER JOIN `default_ps_products_manufacturers` m ON p.manufacturer_id = m.id
INNER JOIN `default_ps_product_x_cats` x ON p.id = x.product_id
INNER JOIN `default_ps_products_categories` c ON x.category_id = c.id";
$result = $this->db
->query($query)
->result();
echo $this->db->last_query();
在该第二示例中,DB ::查询()可以采用的阵列作为将替代任何问号$查询内与相应的值的第二参数(?)。例如说,你需要一些地方值添加到您的查询。
实施例3:
$query = "SELECT DISTINCT m.name, m.id, c.id, c.name
FROM `default_ps_products` p
INNER JOIN `default_ps_products_manufacturers` m ON p.manufacturer_id = m.id
INNER JOIN `default_ps_product_x_cats` x ON p.id = x.product_id
INNER JOIN `default_ps_products_categories` c ON x.category_id = c.id
WHERE c.id=?";
$result = $this->db
->query($query, array(1))
->result();
echo $this->db->last_query();