How to insert same item name with more quantity into the existing item row?

[Ronel]

// This is my actionpage.php
<?php
//session_start();
//Checking User Logged or Not
//if(empty($_SESSION['HR'])){
 //header('location:login.php');
//}

    

$host="127.0.0.1";
$username="root";
$pass="";
$db="loginsystem";

$conn=mysqli_connect($host,$username,$pass,$db);
if(!$conn){
	die("Database connection error");
}



if (isset($_POST["ronel"]))
    {
        $ponum = $_POST["ponum"];
        $podate = $_POST["podate"];
        $remarks = $_POST["remarks"];
        $status =  'stockin';
        $sql = "INSERT INTO purchaseorder(ponum, podate, remarks, status) VALUES ('$ponum','$podate','$remarks', '$status')";
        mysqli_query($conn, $sql);
        $purchaseid = mysqli_insert_id($conn);
 
        for ($a = 0; $a < count($_POST["itemname"]); $a++)
        {
            $sql = "INSERT INTO stock (purchaseid, itemname, poqty,unitno,entrydate,stockqty,deliver) VALUES ('$purchaseid', '" . $_POST["itemname"][$a] . "', '" . $_POST["poqty"][$a] . "','" . $_POST["unitno"][$a] . "','" . $_POST["entrydate"][$a] . "','" . $_POST["stockqty"][$a] . "','" . $_POST["deliver"][$a] . "')";
            mysqli_query($conn, $sql);
        }
 
        //echo "<p>Details has been added.</p>";
    	if(isset($_POST['ronel'])){
            header("location: insert.php");
        }
	
    }
 
?>

2. this is my form

               <form action="actionpage.php" method="post" name="ronel">    
                        <div class="col-25"><label>1. P.O Number:*</label>
                        <input type="number" style="position:absolute; left:14.2%;" name="ponum" placeholder="P.O Number.."></div>
                        <br><div class="col-25"><label>2. P.O Date:*</label>     
                        <input style="position:absolute; left:14.2%;" type="date" name="podate"></div>
                        <br>
                        <div class="col-25"><label>3. Remarks:*</label>
                        <input type="text" style="position:relative; left:3%;" name="remarks" placeholder="Remarks.."></div>       
                        <input type="hidden"  name="status">
<hr>
    <h5>4. Add rows to insert items</h5>
  <br/><table>
        <tr>
            <th>Sl</th>
            <th>Item Name</th>
            <th>P.O Quantity</th>
            <th>Unit No</th>
            <th>Entry date</th>
            <th>Stock Quantity</th>
            <th>Delivery Date</th>
            <th>Delete</th>
        </tr>
        <tbody id="tbody"></tbody>
    </table><br>    
    <button type="button" onclick="addItem();">Add Row</button>
    <input type="submit" name="ronel" value="Submit">
    </form>                 
<script>
    var items = 0;
    function addItem() {
        items++;
 
        var html = "<tr>";
            html += "<td>" + items + "</td>";
        
            html += "<td><select name='itemname[]'> <option value='Pen'>Pen</option><option value='Paper Ream'>Paper Ream</option><option value='Bottle'>Bottle</option><option value='Calendar'>Calendar</option><option value='File'>File</option></select></td>";
            //html += "<td><input type='text'  style='width:120px;' name='itemname[]'></td>";
            html += "<td><input type='number' style='width:90px;' name='poqty[]'></td>";
            html += "<td><input type='number' style='width:90px;' name='unitno[]'></td>";
            html += "<td><input type='date' style='width:125px;' name='entrydate[]'></td>";
            html += "<td><input type='number' style='width:90px;' name='stockqty[]'></td>";
            html += "<td><input type='date' style='width:125px;' name='deliver[]'></td>";
            html += "<td><button type='button' onclick='deleteRow(this);'>Del Row</button></td>"
        html += "</tr>";
 
        var row = document.getElementById("tbody").insertRow();
        row.innerHTML = html;
    }
 
function deleteRow(button) {
    button.parentElement.parentElement.remove();
    // first parentElement will be td and second will be tr.
}
</script>

kindly help needed

[requinix]

Where's the part of your post where you describe the problem?