在不同的事件中获得不同控件的主键

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()