You can write the below code in RowDataBound event.
void gridview1_RowDataBound(object sender,
GridViewRowEventArgs e)
{
var gridview1 = sender as GridView;
if (e.Row.RowType == DataControlRowType.DataRow)
{
string id = gridview1.DataKeys[e.row.RowIndex]["Hid"].ToString();
switch (id)
{
case 12:
e.row.BackColor = Color.Red;
break;
case 13:
e.row.BackColor = Color.Yellow;
break;
case 14:
e.row.BackColor = Color.Green;
break;
}
}
}