前一示例的一個問題是，當(dāng)行可編輯時，主鍵字段 (au_id) 也呈現(xiàn)為文本輸入框。您不希望客戶端更改該值，因為需要它來確定更新數(shù)據(jù)庫中的哪一行。幸運的是，可以通過精確指定每一列相對于可編輯行的外觀，禁用將此列呈現(xiàn)為文本框。為此需在 datagrid 的 columns 集合中定義每一行，使用 boundcolumn 控件分配每一列的數(shù)據(jù)字段。使用此方法，您可以完全控制列的順序，以及它們的 readonly 屬性。對于 au_id 列，將 readonly 屬性設(shè)置為 true。當(dāng)行處于編輯模式時，此列將繼續(xù)呈現(xiàn)為標(biāo)簽。下面的示例說明此方法。
aspx文件里面加入datagrid控件半設(shè)置屬性，代碼如下：
<body ms_positioning="gridlayout">
<form id="form7" method="post" runat="server">
<asp:literal id="message" runat="server"></asp:literal>
<asp:datagrid id="datagrid1" runat="server" width="800" backcolor="#ccccff" bordercolor="black" showfooter="false" cellpadding="3" cellspacing="0" font-name="verdana" font-size="8pt" headerstyle-backcolor="#aaaadd" oneditcommand="mydatagrid_edit" oncancelcommand="mydatagrid_cancel" onupdatecommand="mydatagrid_update" datakeyfield="au_id" autogeneratecolumns="false">
<columns>
<asp:editcommandcolumn edittext="編輯" canceltext="取消" updatetext="更新" itemstyle-wrap="false" />
<asp:boundcolumn headertext="au_id" sortexpression="au_id" readonly="true" datafield="au_id" itemstyle-wrap="false" />
<asp:boundcolumn headertext="au_lname" sortexpression="au_lname" datafield="au_lname" />
<asp:boundcolumn headertext="au_fname" sortexpression="au_fname" datafield="au_fname" />
<asp:boundcolumn headertext="phone" sortexpression="phone" datafield="phone" />
<asp:boundcolumn headertext="address" sortexpression="address" datafield="address" />
<asp:boundcolumn headertext="city" sortexpression="city" datafield="city" />
<asp:boundcolumn headertext="state" sortexpression="state" datafield="state" />
<asp:boundcolumn headertext="zip" sortexpression="zip" datafield="zip" />
<asp:boundcolumn headertext="contract" sortexpression="contract" datafield="contract" />
</columns>
</asp:datagrid>
</form>
</body>
aspx.cs文件中加入下面代碼：
導(dǎo)入using system.data.sqlclient;
定義sqlconnection myconnection;
private void page_load(object sender, system.eventargs e)
{
myconnection = new sqlconnection("user id=sa;password=;initial catalog=pubs;data source=jeff");
if (!ispostback)
bindgrid();
}
public void mydatagrid_edit(object sender, datagridcommandeventargs e)
{
datagrid1.edititemindex = (int)e.item.itemindex;
bindgrid();
}
public void mydatagrid_cancel(object sender, datagridcommandeventargs e)
{
datagrid1.edititemindex = -1;
bindgrid();
}
public void mydatagrid_update(object sender, datagridcommandeventargs e)
{
string updatecmd = "update authors set au_id = @id, au_lname = @lname, au_fname = @fname, phone = @phone, "
+ "address = @address, city = @city, state = @state, zip = @zip, contract = @contract where au_id = @id";
sqlcommand mycommand = new sqlcommand(updatecmd, myconnection);
mycommand.parameters.add(new sqlparameter("@id", sqldbtype.nvarchar, 11));
mycommand.parameters.add(new sqlparameter("@lname", sqldbtype.nvarchar, 40));
mycommand.parameters.add(new sqlparameter("@fname", sqldbtype.nvarchar, 20));
mycommand.parameters.add(new sqlparameter("@phone", sqldbtype.nchar, 12));
mycommand.parameters.add(new sqlparameter("@address", sqldbtype.nvarchar, 40));
mycommand.parameters.add(new sqlparameter("@city", sqldbtype.nvarchar, 20));
mycommand.parameters.add(new sqlparameter("@state", sqldbtype.nchar, 2));
mycommand.parameters.add(new sqlparameter("@zip", sqldbtype.nchar, 5));
mycommand.parameters.add(new sqlparameter("@contract", sqldbtype.nvarchar,1));
mycommand.parameters["@id"].value = datagrid1.datakeys[(int)e.item.itemindex];
string[] cols = {"@id","@lname","@fname","@phone","@address","@city","@state","@zip","@contract"};
int numcols = e.item.cells.count;
for (int i=2; i<numcols-1; i++) //跳過第一、第二和最后一列
{
string colvalue =((textbox)e.item.cells[i].controls[0]).text;
// 檢查在所需字段中是否有空值
if (i<6 && colvalue == "")
{
message.text = "錯誤：“作者 id”、“姓名”或“電話”不允許使用空值";
return;
}
mycommand.parameters[cols[i-1]].value = colvalue;
}
//追加最后一行，將 true/false 值轉(zhuǎn)換為 0/1
if (string.compare(((textbox)e.item.cells[numcols-1].controls[0]).text, "true", true)==0)
mycommand.parameters["@contract"].value = "1";
else
mycommand.parameters["@contract"].value = "0";
mycommand.connection.open();
try
{
mycommand.executenonquery();
message.text = "<b>已更新記錄</b><br>" + updatecmd;
datagrid1.edititemindex = -1;
}
catch (sqlexception e)
{
if (e.number == 2627)
message.text = "錯誤：已存在具有相同主鍵的記錄";
else
message.text = "錯誤：未能更新記錄，請確保正確填寫了字段";
}
mycommand.connection.close();
bindgrid();
}
public void bindgrid()
{
sqldataadapter mycommand = new sqldataadapter("select * from authors", myconnection);
dataset ds = new dataset();
mycommand.fill(ds, "authors");
datagrid1.datasource=ds.tables["authors"].defaultview;
datagrid1.databind();
}
