Cell Editing is another editing mode of jqGrid for PHP. It is quite easy to add the feature. In this case we just need to set the cellEdit option to true.

Sample code:

<?php
require_once 'jq-config.php';
// include the jqGrid Class
require_once "php/jqGrid.php";
// include the driver class
require_once "php/jqGridPdo.php";
// Connection to the server
$conn = new PDO(DB_DSN,DB_USER,DB_PASSWORD);
// Tell the db that we use utf-8
$conn->query("SET NAMES utf8");

// Create the jqGrid instance
$grid = new jqGridRender($conn);
// Write the SQL Query
$grid->SelectCommand = 'SELECT OrderID, OrderDate, CustomerID, ShipName, Freight FROM orders';
// Set output format to json
$grid->dataType = 'json';
// Let the grid create the model
$grid->setColModel();
// Set the url from where we obtain and edit data
$grid->setUrl('grid.php');

//disable the editing of the first column
$grid->setColProperty('OrderID', array("editable"=>false)); 
// Set some grid options
$grid->setGridOptions(array(
   "rowNum"=>10,
   "rowList"=>array(10,20,30),
   "sortname"=>"OrderID",
   "cellEdit"=> true
));
$grid->renderGrid('#grid','#pager',true, null, null, true,true);
$conn = null;
?>

As can be seen you will just need to set cellEdit option to true.