Hello,

This is not supported in lib, but alternate solution is mentioned here.
Refer: http://stackoverflow.com/questions/9655426/jqgrid-setcell-calculated-value

You can set afterSaveCell event in phpgrid control using following code.

$opt["afterSaveCell"] = "function (rowid, name, val, iRow, iCol) { ….. }";
…
$g->set_options($opt);

Above will manage the clientside change on grid. If you want server side table update, you need to write on_update event and run an extra update sql call based on posted data.