asp.net - Deleting is not supported by data source 'SqlDataSource1' in c# -

this cs:

protected void gridview1_rowcommand(object sender, gridviewcommandeventargs e)         {             sqlconnection con = connection.dbconnection();             if (e.commandname == "editrow")             {                 gridviewrow gr = (gridviewrow)((button)e.commandsource).namingcontainer;                                textid.text = gr.cells[0].text;                 textusername.text = gr.cells[1].text;                 textclass.text = gr.cells[2].text;                 textsection.text = gr.cells[3].text;                 textaddress.text = gr.cells[4].text;             }             else if (e.commandname == "deleterow")             {                 gridviewrow gr = (gridviewrow)((button)e.commandsource).namingcontainer;                       sqlcommand com = new sqlcommand("storedprocedure4", con);                 com.commandtype = commandtype.storedprocedure;                 com.parameters.addwithvalue("@id", gr.cells[0].text);                 var id = int32.parse(e.commandargument.tostring());                 gridview1.deleterow(id);                 com.executenonquery();              }         } 

i created student details form, want delete row gridview.

when click delete, shows following error:

deleting not supported data source 'sqldatasource1' unless deletecommand specified.

i'm new .net. getting started,

may know, mistake in above code?

thanks,

    else if (e.commandname == "deleterow")     {         gridviewrow gr = (gridviewrow)((button)e.commandsource).namingcontainer;               sqlcommand com = new sqlcommand("storedprocedure4", con);         com.commandtype = commandtype.storedprocedure;         com.parameters.addwithvalue("@id", gr.cells[0].text);         var id = int32.parse(e.commandargument.tostring());         //comment or remove below line         //gridview1.deleterow(id);         com.executenonquery();         //rebind data after delete         gridview1.databind();     }