Summary Fields

Summary fields is another usefull feature of the grid. The purpose of this feature is to display diffrent statistical information at the footer row in the grid. By default if nothing special is set the SUM (summary) SQL function is used, but you can use any other like AVG (average).
There is no special variable in the grid that operate on this. The summary array should be passed direct to the methods listed below with the parameter named $summary

The structure of the array is:

array("colname"=>"databaseexp")

array("colname"=>array("databaseexp"=>"operation"));

where

colname is the name corresponding to the name in colModel
databaseexp is either database field or database expresion like field1+field2
operation is the database statistical function like SUM, AVG, MIN, MAX, COUNT...

In first case where the operation is not used we asumme that SUM function is used.

In case if your SQL statement look like:

$grid->SelectCommand = "SELECT a, b , c+d AS e FROM table";

and you want the summary of c and d field to be displayed in the grid, the array should like this

$mysumarray = array('e'=>array("c+d"=>"SUM"));

Related methods

exportToExcel
queryGrid
editGrid
renderGrid

Let ilustrate this again using the example.

Our goal is to display at the footer row the avarage of the Freight field.
The html code should be:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>PHP jqGrid Class Example</title> 

<link rel="stylesheet" type="text/css" media="screen" href="themes/redmond/jquery-ui-1.7.1.custom.css" />
<link rel="stylesheet" type="text/css" media="screen" href="themes/ui.jqgrid.css" />

<script src="js/jquery-1.3.2.min.js" type="text/javascript"></script>
<script src="js/i18n/grid.locale-en.js" type="text/javascript"></script>
<script src="js/jquery.jqGrid.min.js" type="text/javascript"></script>
<script type="text/javascript">
jQuery(document).ready(function(){
....
// Craeate the grid manually
jQuery("#grid").jqGrid({
"colModel":[
     {"name":"OrderID","index":"OrderID","label":"ID","width":60, "key":true},
     {"name":"OrderDate","index":"OrderDate"},
     {"name":"CustomerID","index":"CustomerID"},
     {"name":"Freight","index":"Freight"},
     {"name":"ShipName","index":"ShipName"}
],
"url":"querygrid.php",
"datatype":"json",
"jsonReader":{repeatitems:false},
"pager":"#pager",
"footerrow":true,
"userDataOnFooter": true
});
// Set navigator with search enabled.
jQuery("#grid").jqGrid('navGrid','#pager',{add:false,edit:false,del:false});
......
});
</script>

</head>
<body>
......
<table id="grid"></table>
<div id="pager"></div>
.......
</body>
</html>

Note the two additional settings in the grid definition - footerrow and userDataOnFooter. The first setting enables the footer row the second uses the userData array to put the values on the footer row.

The PHP code should be:

<?php
require_once 'jq-config.php';
// include the jqGrid Class
require_once "php/jqGrid.php";
// include the PDO driver class
require_once "php/jqGridPdo.php";
// Connection to the server
$conn = new PDO(DB_DSN,DB_USER,DB_PASSWORD);

// Create the jqGrid instance
$grid = new jqGrid($conn);
// Write the SQL Query
$grid->SelectCommand = 'SELECT OrderID, OrderDate, CustomerID, Freight, ShipName FROM orders';
$grid->dataType = "json";

$avg = array('Freight'=>array('Freight'=>'AVG'));

// pass the avg array to the grid
$grid->queryGrid($vg);
?>