我设法通过将 from 子查询放入初始选择语句中来使查询工作:

I managed to get the query to work by putting the from sub_query into the initial select statement :

$this->db->select("*, 
  (select image_path from image where image_table = 'model' and image_table_id = model_id
  group by image_table_id limit 1) as ModelImg FROM 
  (SELECT * FROM $view where offer_table = 'derivative' order by offer_order) x");