★当把DataSet绑定到Datagrid...... 当把DataSet 绑定到Datagrid控件, 并利用DataAdapter对象修改数据库 如: dim adp as new OleDbDataAdapter(stradp,conn) dim ocb as new OleDbCommandBuilder(adp) adp.DeleteCommand = ocb.GetDeleteCommand() adp.Update(ds,"Orders") -------------------------------- 执行删除操作时,如我们加入这样一个方法: sub mydatagrid_delete(sender as object, e as datagridcommandeventargs) dim dt as new DataTable() dt = ds.Tables("Orders") dim dr as DataRow dr = dt.Rows(E.Item.ItemIndex) dr.delete 'dr.AcceptChanges '曾经尝试使用彻底删除,发现adp自动更新回数据库时,无法自动生成相应的sql语句 '解决删除当前页最后一项时出现的页索引异常 ' ***************************************************************** dim lastEditPage as integer = mydatagrid.currentPageIndex If (mydatagrid.pageCount - mydatagrid.currentPageIndex) = 1 and mydatagrid.Items.Count = 1 Then If mydatagrid.pageCount > 1 Then lastEditPage = LastEditPage - 1 Else lastEditPage = 0 End If End If mydatagrid.currentPageIndex = lastEditPage ' **************************************************************** session("orderList") = ds mydatagrid.edititemindex = -1 mydatagrid.datasource = ds.tables("Orders") mydatagrid.databind() end sub 当由第一个开始逐个删除时出现了异常,发现在删除第二时,删不掉,即原来的dr(2)没有自动变为dr(1)。如果我们使用dr.delete dr.acceptChanges则可以自动变化,但是上面说明了,则无法使用自动更新回到数据库。我们必须获得删除时的实际索引,所以就用了一个本方法,在当前的ds中另外建了一个Table,保持同步删除,但是在Table的id列中,保存实际的索引值,具体代码如下: 解决dr索引的一个办法: dim orderTable as new DataTable() '建一个临时表用来保存索引,保持同步删除 dim theNewRow as DataRow dim dc as DataColumn orderTable.TableName = "orderId" ds.Tables.add(orderTable) dc = new DataColumn() dc.ColumnName = "id" orderTable.columns.add(dc) dim dcKey() as DataColumn = {orderTable.Columns("id")} orderTable.primaryKey = dcKey dim i as integer For i = 0 to (ds.Tables("Users").Rows.Count - 1) theNewRow = orderTable.NewRow() theNewRow("id") = i.toString() orderTable.Rows.add(theNewRow) Next 上述删除功能中加的代码,替换 dr = dt.Rows(e.Item.ItemIndex): dim drOrder as DataRow drOrder = ds.Tables("orderId").Rows(E.Item.ItemIndex) dim currentOrder as integer = CInt(drOrder("id")) + mydatagrid.currentPageIndex * mydatagrid.PageSize dr = dt.Rows(currentOrder) drOrder.delete 如果有更新功能,则替换dr = dt.Rows(e.Item.ItemIndex): dim drOrder as DataRow drOrder = ds.Tables("orderId").Rows(E.Item.ItemIndex) dim currentOrder as integer = CInt(drOrder("id")) + mydatagrid.currentPageIndex * mydatagrid.PageSize dr = dt.Rows(currentOrder) |
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