i am creating dynamic multiple row to store data into database. all working fine on front end as rows created and also multiple value selected in docname1 field by selected choosen. but the issue is that when i process code, then its save data sucessfully but docname1 storing only first value, rather than multiple selected one.

here is php code

<td><Select class="form-control text-end" name="country[]"  id="iii"   required>
<td><Select class="form-control text-end" name="state[]"  id="jjj"   required>
<td><Select class="form-control text-end" name="city[]"  id="kkk"   required>
<td><Select class="form-control text-end chosen-select" name="docname1[][]"  id="lll" multiple  required onfocus="Calc(this);">

and below is processing code

<?php

if(isset($_POST['submit']))
{
// getting all values from the HTML form

        $country = $_POST['country'];
    $state = $_POST['state'];
    $city = $_POST['city'];        
        
  $docname1 = $_POST['docname1']; // Multidimensional array
          
}

for ($i = 0; $i < count($city); $i++) {

$docname1Str = isset($docname1[$i]) ? implode(',', $docname1[$i]) : '';
             $sqlInsertItem = "
            INSERT INTO iap4(country, state, city,  docname1) 
            VALUES ( '{$country[$i]}', '{$state[$i]}', '{$city[$i]}', '$docname1Str')
        ";


$rs1 = mysqli_query($con, $sqlInsertItem);
        

}

  echo "<pre>";
print_r($docname1);
echo "</pre>";


echo "<pre>";
print_r($_POST);
echo "</pre>";

?>