Cannot Update Dynamic Fields in Codeignitor

Hi
I created Dynamic fields for billing information,item name,qty,rate,total fields are loaded dynamicall by click Add New.When i want to update active records in dynamic fields there some Database Error. Any For loop issue or anyone suggest

public function updatebill(){
$currentBillId=$this->input->post('bill_no');
$update_billno=$this->input->post('itemData[1[bill_no]');
$updatePostData=$this->input->post('itemData');
$this->load->model('billmodel');
$this->billmodel->update_bill_details($currentBillId,$updatePostData);
}

I have checked $cuurentBillId(having bill Id),$updatePostData(having input fields data which i want to update on the table)

public function update_bill_details($currentBillId,$updatePostData){
$bill_no=$this->input->post('itemData[1[bill_no]');
$item_name=$this->input->post('itemData[1][item_name]');
$item_quantity=$this->input->post('itemData[1][item_quantity]');
$item_rate=$this->input->post('itemData[1][item_rate]');
$item_total=$this->input->post('itemData[1][item_total]');
$item_tax=$this->input->post('itemData[1][item_tax]');
$without_tax=$this->input->post('itemData[1][without_tax]');
$item_grand_total=$this->input->post('itemData[1][item_grand_total]');
$item_income_tax=$this->input->post('itemData[1]item_income_tax');`for($i=1;$i<sizeof($updatePostData); $i++)`
{
$result=array(
'item_name'=>$item_name,
'item_quantity'=>$item_quantity,
'item_rate'=>$item_rate,
'item_total'=>$item_total,
'item_tax'=>$item_tax,
'without_tax'=>$without_tax,
'item_grand_total'=>$item_grand_total,
'item_income_tax'=>$item_income_tax);
$this->db->where('bill_no',$i);$this->db-> omegle voojio set($result[$i]);
}