title: Insert Batch, and if duplicate key Update in Codeigniter 3 HMVC
body: <p>Is there any method of performing in <code>insert_batch</code> and if the key already exists, UPDATE that row in codeigniter 3 HMVC ? </p>
  
  <p>I have gone through the documentation and found only insert_batch and update_batch and found from some old discussions but with Codeigniter 2 also when i run on my HMVC it's doesn't work. </p>
  
  <p>how to update the row with duplicate key in active records (MySQL Query : On Duplicate Key Update) ? And what happens if one row fails to be inserted or updated in insert_batch ? All insertion fails or only that row ?</p>
  
  <p>Thank you. </p>