datalist的 datalist_ItemCommand 得到主键：datalist.DataKeys[e.Item.ItemIndex];
RadioButtonList得到绑定的Value RadioButtonList.SelectedValues;
dropdownlist得到主键：
int id2=Convert.ToInt32(BranchDrop.SelectedValue);id = Convert.ToInt32(BranchDrop.SelectedItem.Value);
gridview(RowDeleting): int id =Convert.ToInt32(gridview1.DataKeys[e.RowIndex].Value.ToString());
gridview1_RowEditing: id2 = Convert.ToInt32(gridview1.DataKeys[e.NewEditIndex].Value.ToString());
Gridview1_RowDataBound(object sender, GridViewRowEventArgs e)事件中获取主键：Gridview1.DataKeys[e.Row.RowIndex][0]
在Gridview1_RowCommand事件中获取主键：
Gridview1.DataKeys[Convert.ToInt32(e.CommandArgument)][0]
datagrid_itemcommand:
Dim ID As String = Me.datagrid1.dataKeys(e.item.itemIndex).toString()
PS:
前几天在用GridView删除新闻时，要删除新闻相应的图片，需要获得删除行的主键，我当时写的是：
gridview1.datakeys[e.index].tostring()
结果就报错了，后来找到了原因，正确的应该是：
gridview1.datakeys[e.index].value.tostring()
记得要加 .value ,大家不要再犯和我一样的错误哦
