When a column is editable, you can select how end-users will edit it. This is controlled by the edittype property and current has five different options - text, textarea, select, password, checkbox.

In addition to that, you can specify the values end-users will see in name:value pairs in the editoption values property of Columns - this is especially useful for SearchType DropDown. Here is an example

$grid->setColProperty("CustomerID",array("editoptions"=>array("value"=>"1:One;2:Two")));

There is a more easy way - in this case you just need to call setSelect function and set either SQL or array of values.

check the PHP tab for details
<?php 
require_once '../../../../php/demo/tabs.php';
?>
<!DOCTYPE html>
<html>
  <head>
    <title>jqGrid PHP Demo</title>
    <link rel="stylesheet" type="text/css" media="screen" href="../../../../css/jquery-ui.css" />
    <link rel="stylesheet" type="text/css" media="screen" href="../../../../css/trirand/ui.jqgrid.css" />
    <link rel="stylesheet" type="text/css" media="screen" href="../../../../css/ui.multiselect.css" />
    <style type="text">
        html, body {
        margin: 0;            /* Remove body margin/padding */
        padding: 0;
        overflow: hidden;    /* Remove scroll bars on browser window */
        font-size: 75%;
        }
        
    </style>
    <script src="../../../../js/jquery.min.js" type="text/javascript"></script>
    <script src="../../../../js/trirand/i18n/grid.locale-en.js" type="text/javascript"></script>
         <script src="../../../../js/trirand/jquery.jqGrid.min.js" type="text/javascript"></script> <script type="text/javascript">         
    $.jgrid.no_legacy_api = true;
    $.jgrid.useJSON = true;
    $.jgrid.defaults.width = "700";
    </script>
     
    <script src="../../../../js/jquery-ui.min.js" type="text/javascript"></script>
  </head>
  <body>
      <div>

          <?php require_once("grid.php");?>
      </div>
      <br/>
      <?php tabs(array("grid.php"));?>
   </body>
</html>
grid.php.
<?php
require_once '../../jq-config.php';
// include the jqGrid Class
require_once ABSPATH."php/PHPSuito/jqGrid.php";
// include the driver class
require_once ABSPATH."php/PHPSuito/DBdrivers/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, CustomerID, Freight, OrderDate, ShipCity FROM orders';
// set the ouput format to json
$grid->table = 'orders';
$grid->dataType = 'json';
// Let the grid create the model
$grid->setColModel();
// Set the url from where we obtain the data
$grid->setUrl('grid.php');
// Set some grid options
$grid->setGridOptions(array("rowNum"=>10,"rowList"=>array(10,20,30), "sortname"=>"OrderID","height"=>150));
// Change some property of the field(s)
$grid->setColProperty("OrderDate", array(
    "formatter"=>"date",
    "formatoptions"=>array("srcformat"=>"Y-m-d H:i:s","newformat"=>"m/d/Y"),
    "search"=>false,
    "editable"=>false
    )
);
$grid->setColProperty("OrderID",array("editable"=>false));
$grid->setColProperty("ShipCity",array("editable"=>false));
$grid->setSelect('CustomerID', "SELECT CustomerID, CompanyName FROM customers");
// Enable toolbar searching
$grid->navigator = true;
$grid->setNavOptions('navigator', array("del"=>false,"excel"=>false,"search"=>false,"refresh"=>false));
$grid->setNavOptions('edit', array("height"=>'auto',"dataheight"=>"auto","width"=>'auto'));
$grid->setNavOptions('add', array("height"=>'auto',"dataheight"=>"auto","width"=>'auto'));
// Enjoy
$grid->renderGrid('#grid','#pager',true, null, null, true,true);