I want to group by date Grid view Subtotal and grand total

hi...
I think you can do this in 2 ways.

1) If You use sql server and use Stored Procedure then
Write query with Group by and rollup which return your required result.
2) You can create result set like
Fetch 2 Datatable one for Distict Date and One for Date with Detail

 //Create Temp Table
  Datatable tmpdt=new Datatable();
//Add Data Columns in tmpdt.

  //Loop For Date
  for(i=0;i<dt.rows.count;i++)>
  {
    Decimal totAmt=0.0;
    for(j=0;j<=dtDetail.rows.countj++)
    {
       if(dt.rows[i]["Date"]==dtDetail.rows[j]["Date"])
       {
           totAmt=totAmt+convert.toDecimal(dtDetail.rows[j]["Date"]);
       }
    }
    Datarow dr;
    dr=dttmp.NewRow();
    //Add Detail
    tmpdt.rows.add(dr);
  }

// Finally set data source to grid