How to use CASE in MySQL using CodeIgniter with joins

I am using CodeIgniter,

I am able to export the data. I have a column called "status" in the excel sheet. In the status column I am getting 1,0,0,1,-1,2.

Now I have to display the string name in the excel sheet like.

-1="Pending"
 0="Cancel"
 1="Create"
 2="Verified"

I know I have to use CASE but I don't know how to use with Codeignator.

I tried below code.

$this->db->select('tbl_customer.*,tbl_customer_shipping.*,product_order.*, CASE 
WHEN product_order.o_order_status =-1    THEN "Pending" 
WHEN product_order.o_order_status =0    THEN "Cancel"
WHEN product_order.o_order_status =1    THEN "Create"
ELSE "Verified"
END CASE');
$this->db->from('tbl_customer');
$this->db->join('tbl_customer_shipping', 'tbl_customer.cust_id=tbl_customer_shipping.cust_id', 'LEFT');
$this->db->order_by('product_order.o_date_of_added','DESC');

$query = $this->db->get();
$result = $query->result();

But it's not working

I am getting a syntax error

Message: syntax error, unexpected 'CASE' (T_CASE)

Would you help me out in this?

Finally, I found My solution. I forgot to add the name of the column at the end of the case and I used a double inverted comma.

$this->db->select("tbl_customer.*,tbl_customer_shipping.*,product_order.*,CASE 
    WHEN product_order.o_order_status =-1    THEN 'Pending'
    WHEN product_order.o_order_status =0    THEN 'Cancel'
    WHEN product_order.o_order_status =1    THEN 'Create'
    ELSE 'Verified'
END as o_order_status");