c# - Serialize data from database in JSON Format -

i creating web service in asp.net serialize data in json format, , access webservice via jquery

using system; using system.io; using system.net; using system.web; using system.linq; using system.web.hosting; using system.web.services; using system.web.script.services; using system.collections.generic; using system.web.script.serialization; namespace chart_webservice {     /// <summary>     /// summary description service     /// </summary>     [webservice(namespace = "http://tempuri.org/")]     [webservicebinding(conformsto = wsiprofiles.basicprofile1_1)]     [system.componentmodel.toolboxitem(false)]     [scriptservice]     // allow web service called script, using asp.net ajax, uncomment following line.      // [system.web.script.services.scriptservice]     public class service : system.web.services.webservice     {         [webmethod]         [scriptmethod(usehttpget = true, responseformat = responseformat.json)]         public datatable getdata()         {            string constr = configurationmanager.connectionstrings["constr"].connectionstring;            using (sqlconnection con = new sqlconnection(constr))            {                using (sqlcommand cmd = new sqlcommand("select * customers"))                {                    using (sqldataadapter sda = new sqldataadapter())                    {                        cmd.connection = con;                        sda.selectcommand = cmd;                        using (datatable dt = new datatable())                        {                            dt.tablename = "customers";                            sda.fill(dt);                            return dt;                        }                    }                }            }        }     } } 

please me complete solution because not have idea complete hope @ guys!

i not return datatable. can use raw ado.net , fill result simple dictionary<string, object>. newtonsoft.json can serialize dictionary , return it.