jQuery Grid Plugin - jqGrid

Is it possible for mySQL queries that build jqGRID to be generated dynamically by the user? Any examples?

For example, the user might select the fields she wants to see rendered in jqGRID from a drop down menu, say "Field_1" and "Field_2".

so this would be used to construct the following:

var urlString = 'server.php?user_fields="Field_1,Field_2"'

then the url parameter for jqGRID could be set to

url: urlString

Is the idea above even feasible to try to implement?

Is there a full example?