codeigniter unable to insert multiple row data to database

Instead of this code in your view:

PHP Code:

echo "
  <input name=\"iddisc".$n."\" type=\"text\" value=\"".$iddisc."\" class=\"textbox\" />
  <input name=\"dname".$n."\" value=\"".$discount_name."\" type=\"text\"  />
  "; 


I recommend:

PHP Code:

echo form_input('iddisc[]',$iddisc[$n],'class="textbox"');
echo form_input('dname[]',$discount_name[$n]); 


since you are using CI's form helper anyway.
By using square brackets at the end of the input name, $this->input->post('iddisc'); will return an array with all the iddisc input fields.
To process this in your controller (or model), do this:

PHP Code:

$iddiscs = $this->input->post('iddisc');
$dnames = $this->input->post('dname');

foreach ($iddiscs as $index->$idd) {
  $data[] = array(
    'iddiscount'   => $idd;
    'discountname' => $dnames[$index],
    'status'       => 1,
  );
}